Help: My Ball python is going into a ball quickly in his hide

I just got this 4 yr old male Butter 4 days ago, he looks healthy and the previous owner had no issues. But I had noticed today(he did this twice) the room is silent and dark, I just hear a noise from his tank and he’s suddenly gone into a ball inside his hide! First three days I didn’t notice this behaviour.

since I got him I changed his tank- 20g to 40. -replaced his old substrate of newspaper to coco soil (my other snakes use this) -I added a thermostat to his set up, and a heating light. The previous owner had neither of these.

humidity and temps are great. I’m not sure what’s going wrong. He seemed fine in the new enclosure past few days.

Congratulations on the new BP. I hope he has a long healthy life in your care. If he's only been with you for 4 days he's not fully acclimated to the new habitat yet. He'll probably be nervous for a while and either hiding or trying to escape. Aside from cage maintenance I try to leave my new snakes completely alone for at least a couple of weeks or until they've eaten a few times.