i have heard of a few stories of snakes staying on the cool side. alot of people say that it is a natural thing for them to find a cool spot to hide. You said your snake has mites? i would think it would be best for it to be on the warm side because they seem to "heal" faster that way. i know it's a late response. i haven't been on this website for a while. i hope your snake is healthier now.
Rebekah