Vomiting from new enclosure setup?

[Polemarchus]

Good evening all,
So, for the past little bit, I have been lurking in the shadows with my new guy, Monty (yeah, I know…I let my wife name him). Unfortunately, my first post comes as an odd one. Bottom line up front: I woke up last night to a weird noise coming from his enclosure so I checked on him and saw that he had vomited on the wall of the enclosure (it's been 6 days since he fed). Sorry if it’s lengthy, but might be easier to get the info out).

Some info about Monty (I will give you the abridged version of his log):
Got him 3/10 and he has been staying in a 18QT tub type setup (paper towels as substrate) so I could keep track of every move he made in a controlled environment. Cold side about 78-80F and hot side 90-93F with UTH controlled by VE-300, humidity 50-60%.
Initial weight: 373g
Waited 5 days before feeding him his first feed and kept on his weekly feedings (5-7 day feeds of about 50-60g F/T rats) He has been eating like a champ and never missed a beat. He peed and pooped 4 days after the initial feeding.
First handling session was 48 hours after the second feeding. It was a memorable handling session as he was on my lap and 3 minutes in, I felt his pee running down my side and as I picked him up to see what it was, he found it necessary to take a huge poo on me. So, I’m not sure I would call that a ‘handling session’. The remaining handlings have been short ones, about 7-10 minutes each time, about 3 times a week and never within about 2 days of feeding.
He has left urine, urates, and poo fairly often and by 3/31, he had shed and got up to 480g after the pee/poo/shed.
He stays in his hide during the day and seems to cruise at night, as usual.
All of this has been a pretty textbook transition from him and it was going fairly well.

Recent events:
This past weekend, I was going up to my house in Maine for 4 days so I brought him with me so I could make sure he was with water and all that (and so the kids could see him). Put him in a snake sack and then put him in his empty tub and made the 2.5 hr drive back home. He had pooped and peed already that day and it had been 3 days since his last feeding. Got there, set up his cage like normal, and he was peachy for the trip and we made our way back yesterday morning. He was handled a couple times as he peed and pooped again over the 4 days while there.
I had his new cage set up and all I had to do was check the temps after I moved the VE-300 over to monitor the new cage (24x14x12 PVC cage from dragons4you.net). Two identical hides for cold and hot, right and left and cypress mulch for the substrate (the stuff meant for reptiles from Amazon), and a water bowl on the cold side. Cold on the left (80F) and hot on the right (91F). The hottest point on the hot side was the top of the hide itself at 93F (Radiant Heat Panel controlled with VE-300). Humidity was a bit high from the cypress mulch. I tried to dry it in an open tub over the last few days, but still retained moisture and humidity was 60-70%.
So, all the temps are stable and it’s time to introduce him to the enclosure. I put him in, he explored, smelled everything, and drank for about 30 seconds (I’ve also seem him drink many times in the past). He ended up resting in the middle of the cage near the sliding doors so I went to bed. A few hours later, I hear a wear whooshing sound from his enclosure and check it out, only to find the vomit on the back wall of the enclosure. I pull him out, wipe him down with a damn paper towel and then clean up the mess. The vomit had a little gelatinous mixture with a little bit of fur and some unknown bits. Temperatures didn’t seem off and humidity was 67%. He seemed as if nothing happened. Moving around in the temporary tub, tongue flicking, moving and looking normal. After I put him back in, he went into his cold hide and there wasn’t much I could do. About 5 hours later, I woke up to the same thing with him over his water dish, but this time it was just liquid (he’s pooped and peed so much since his last feeding that there’s not much in his belly. I took him out again, wiped him down and moved him back into his old tub setup that I know was working well before. He looked normal and did all his standard behaviors. He pretty much went right into his hide and I think he has been there all day. I have checked on him a few times throughout the day and he seems like normal from what I can tell. It’s been 16 hours since the episode. As he looks and acts healthy, I didn’t take him straight into the vet. The past weekend might have been too much for him and them compounded by swapping to a new tank that might have been too hot/humid? and just too much for him.
I will monitor him through the night and take him to the vet tomorrow if necessary. I intend on waiting 10-14 days before any feeding to build up his stomach bacteria and no handling for a while. Is there anything I should be on the lookout for? What things could have caused this? I’ve attached some recent pics so you can see what he looks like.
Thanks,
Jeff