I missed one on the head count one night... my alpha rooster to boot (still don't know how I did it, I swear I counted that night...). The next morning a friend stopped by just as I was opening the garage to let the cats out so I was talking to her before going to check the chickens and my rooster just come wandering around the corner. I was like what, how did you get out? I've had chickens fly out of my 6 foot run before, but it was a young (and flighty) EE, and my rooster is a very heavy Wyandotte, so I thought maybe I'd forgotten to shut the gate to the run and he'd gotten out after the auto door had opened. WELL, not ONLY was the gate shut tight, but the auto door hadn't even opened, so all the other chickens were still shut up in the coop... So there is no explanation other than I left him out overnight. I felt like the worst chicken keeper ever. But he was fine, and very happy to be home. I have no idea where he roosted for the night, but I'm sure it was somewhere relatively safe. Needless to say, I count twice now.
Glad your chickens made it home safely! It's always such a huge relief when these things end well!