It's not physically possible for them to push their own tubs open from the inside...unless there was already a gap large enough for them to wedge a nose into. Wouldn't take much of a gap to allow that to happen though, so be sure to double check. Glad you found him and got him back into his home safe and sound. One night of cool temps probably won't hurt him, but keep an eye on him for the next couple of weeks to watch for any signs of RI.

Sorry you had such a rough morning! I hope you get a chance to slow down and baby yourself...drink some hot broth and take a good long nap!!