I don't use the power outlets or usb ports on planes--haven't so far, anyway--but I'm not surprised. I sat next to someone the other day and watched her USB cord fall out of the port repeatedly within moments of it being plugged in. I checked to help her and make sure it wasn't her, and it was the port, damaged or worn out. You will run into this anywhere outlets are used frequently by different people (and their plugs). Airport gates, Airline clubs, hotel rooms...… It's wear and tear on the receptacle. It isn't you.