I did. I experienced this last year flying YUL - Nashville on two AA first class award (mom and me). There was a mechanical difficulty on the plane and we didn't leave Montreal. Everyone was dumped off the plane, I raced up ahead of mom and was the first person in line to get tix fixed.

Our new flights were on US Airways via Pittsburgh, also in first class. we had enough time to get over to the gate and wait for boarding. Yours truly the card addict had her USAirways card with her and got full credit for the flights. Mom was signed up on the spot and her passes had to be mailed in but was credited. We didn't get fed though, so I lugged Burger King onto the flight.

[Homer Simpson impression... mmmm, chicken whoppers with free rum drinks....]