It worries me because he's gotten 4 meals in him and yet to have a bowel movement. There's no bulge in him at all so I don't know where it's all going.
My little "rescue" was the same way - he ate and ate and ate... didn't poop until well after third third meal! He's also a fan of the cool side as well, even though his temps are spot on (80 on cool side, 91 warm side).

During the day he's hiding, but at night he's a little acrobat. Have you checked on yours in the middle of the night? However, he may still sense you coming in advance and zip into the nearest hide if he's out and about.

Just my thoughts... but I'm no expert.