From what I understand the size of the tub can sometimes upset some ball pythons too. I found that some snakes can get stressed from moving into a larger space. Make sure the snake has plenty of hiding spots or is secluded enough. I have an open sided rack now with four 100 gram babies i just got. Three of them are doing, great but one is very defensive about movement outside the rack. Keep an eye on his body language to see if he is stressed after making the switch.