Originally Posted by
demosthenes1
I've seen it the other way. The new boarding pass gets printed out and left at the desk if Mr. A doesn't respond to an announcement. Then the GA will catch him as he boards.
This has happened to me twice in the last year, once on CO, once on UA. They swiped my boarding pass only to hear it squawk about it being for the wrong seat. Both times, I was running from a late arriving connection so it's nice that they didn't skip over me.