I had introduced my ADF to my tank with my one betta a few months ago. Being nervous, I kept the heater off at night while my roommate and I slept in our warm room. The night I finally sucked it up and turned it on, he got too hot, jumped out, hopped allllll the way over the the shower (a good twenty feet away, under a door and around countless dorm room obstacles), and dried up on the linoleum.
MORAL OF THE STORY: Don't let this happen. Be more careful than I was.