Showed up the the airport on the wrong day one time

This was when I was travelling to Los Angeles very regularly. I showed up to LAX for my normal flight home on Thursday. Machine could not find reservation. Went to AAgent. She saw I had a reservation for FRIDAY. I thought that was odd, then remembered I had booked a FRIDAY return instead of my more normal Thursday return. I can't really recall why I booked a Friday return. I was booking flights a few weeks in advance. I had some reason for doing it, but then sorta forgot about that trip being an "odd" one.

They managed to get me on the flight I wanted. No muss. Not much fuss. Only had to pay a change fee. They waived fare difference fees. Being PLT has it's AAdvantages.