We got him on 1/21 from PetCo (I know...I know) First snake but not first reptile, we've had a great BD for many years and a few Crested Geckos. I'd like to think I'm good understanding husbandry

He ate twice, very enthusiastically. F/T.
We came home with hoppers, he actually ate 2 in a row on the 1st feed. Moved him up to small mice (19-20g) for subsequent feeds and that seemed to be a good size.

When I went to feed him the 3rd time he was blue and he didn't eat (understandably). Left him alone to do his thing. He finally shed on 2/5 overnight. He shed nicely & everything came off, mostly one piece. Left him alone the day after shed, tried to feed him the next day Feb 7th. Not remotely interested. Have tried 3 more times, giving him a few days between attempts. Nada. I have perfectly my zombie dance. Aside from thawing in warm water, have also warmed up at the last minute with a hair dryer. Have left mouse in his enclosure overnight each time. He's not having it. The first two feeds I had put the mouse & snake in a low plastic container inside the enclosure and he was fine with that. Have tried repeating that and also just bringing the mouse to him.

On the non feed days he does come out and cruise around the tank at night, he seems healthy & active (for a snake). No signs of mites or RI.

He was 122g when we got him. Went up to 136g (hadn't pooped though) and now he's down to 130g. He is starting to look a little skinny. He's probably about 4 months old though I don't have a hatch date on him. I have seen him drinking a few times so hopefully he's keeping hydrated.

It is a larger cage (custom melamine from when we had the BD) but he's got 3 hides and a lot of "stuff" filling up the floor space. Heated with a RHP on a thermostat. Hot side consistently 92-93, cooler zone is a gradient in the 80's. Measured with 2 different temp guns plus a digi inside to monitor ambient (mid 80s).

The one odd thing is he does prefer to be on the cool side pretty much exclusively. I thought maybe he liked that particular hide better so I switched them around. Nope, went to the cool side again.
humidity 50-60's.

If he's just being stubborn, ok but I want to know when to go from new mom worried to actually worried.

Feeding live would be an extremely last resort for me. I will do it if it comes down to saving his life but I thought I was safe getting a snake that was already used to F/T. I also don't know where I'd even find live mice, there aren't any reptile stores around that I'm aware of. I'm in Monmouth county, I've seen a few NJ folks here so if you have any local suggestions I'd love to hear it.