Originally Posted by
bluedemon211
I'm sure you know the facts far better than anyone. That said, it wouldn't surprise me if the GA upgraded you, printed the BP, and noted you had boarded. Instead of stopping the usual frenzy as they are trying to get the flight out on time and going on board, they might have simply said to the Pass holder, "would you mind walking this on the plane and giving it to the upgrader and you take his seat in Y". That's happened to me twice in the last couple of years.
That actually makes a lot of sense as to how it happened. If I recall correctly, it was a full flight, like most ORD-EWR flights were, so this seems to be very likely. I always wondered how he got away with taking my pass.