My brother told me a story about when Krispy Kreme was a new store at The Fort. It was near closing time and he'd succeeded in getting a dozen despite the long line. So the guard closed the doors a little past closing time to satisfy everyone until they'd run out of doughnuts. However, a mob formed outside, complaining that there were still doughnuts. They were referring to the ones passing through the conveyor belts-- tomorrow's batch. The mob was growing and so was the murmuring; one even said loudly that they'd go to Gonuts Donuts instead if they didn't get their doughnuts. (Guard: ummmm... okay.) According to my brother, these people all could have used a lot less doughnuts in their lives.
Yikes. Desperate much? Anyway, the shop succumbed and reopened after closing to give them their precious doughnuts.
If there's a lock on the door, that's a sign from God. "Stop stuffing yourself," He's saying. Or you could use your own dignity as a gauge. Never complain. Never mob. Brush it off.