Reply To: I need help
Hoping I can help. Usually there’s a zoologist here with great advice, but I havent seen her in months..
Anyway, I tend to like slight larger enclosures than required, but 40 is the minimum for an adult ball python. So even though I’d go bigger, it’s not a bad size by any means. As long as you’re sure about the temp and humidity, the next reason it may be doing this is if you don’t have a proper heat gradient. Is all the heating elements on the same side of the tank (For example, all on the right side)? Aside from any uv you may be using, I mean. Uv can be throughout the whole tank from what I’ve learned, though there must be an area they can get into shade and out of the light.
Without this heat to cool side temp difference/gradient, he won’t be able to properly regulate his temp to be comfortable. Hence trying to leave the area for a cooler spot. Most heat is absorbed through their bellies so glad to hear of the heat mat. If not for that I’d recommend placing slate under the heat lamp/emitter.
Now, if you do have a heat gradient, I’ll have to think of any other reasons and/or do more research. Gradient aside, Your tank sounds great though, really.