Snakes can have odd and unpredictable behaviors that we don't really understand. Despite our best efforts to provide immaculate caging, they will still do whatever they want. Frequently my largest boa will stay on the cold side for a week after eating a large meal. I check all my temps daily, and it used to drive me nuts that she didn't want to be on the hot spot right after eating. Yet she eats, digests, sheds and defecates perfectly fine. These animals know they conditions they need. Don't worry.