The crappy thing is when you hold a seat for 6 months then go to check in and are told that you are in another seat... even though the website still shows you in your original seat.

Had this happen on a flight this past week and went up to the GA to ask what happened. She said she wasn't sure and couldn't tell "but at least you're in First!" (6D on a 757).... that was fine until the young kid on behind me patted me on the back and said "congratulations"....