Yes, rust.
My rear passenger door lip is rusting in a few spots. The lip is starting to peel away from the door across the bottom and parts of the side. This is not surface rust. It's from the inside out. There has never been any body work done, as far as I know. That is the only place that has any rust. The rest of the doors are perfect, as well as the tailgate. I know it's old, 2001, but there shouldn't be rust this bad. My 96 accord with 260k isn't rusting, neither is the 98 Jetta. I talked with a friend who does body work, and he suggested I get a new door instead of fixing it. He said it would be cheaper in the long run, and the issue wouldn't come back for a long time.