So after the party on Friday, my boss casually mentioned something to me. I told her I'd think about it. So less than 6 days after my last day, I got my key back.
She pretty much made me an offer I couldn't refuse. She asked if I would be interested in being a substitute on the management team. So if there was a day she or the other managers couldn't be there, I could open the building so that the other person wouldn't have to work a 12 hour day. I'd get plenty of notice and if I couldn't work it, that was fine. I would just have to say that I couldn't.
So today I got my key back. It's back on my chain where it belongs. Guess they really do love me.