As I was reading this thread, I was thinking like a Devil's Advocate.

I would expect with the security at Airports today, that if you bought a ticket, checked in, and then cancelled the ticket, the airline would have to A) recheck to make sure that you were not on Board, B) Check to make absolutely sure that you did not check in any luggage. This could also entail the plane and Gate area being evacuated and the luggage being off-loaded. The end result could be a several hour delay for the other passengers on the flight.

I would suggest calling the airline to find out about getting a pass to the gate to meet Grandmother.