I have a 2002 Ford Focus, and was cleaning the usual winter salt off the car the other day when I noticed that the passenger side door had small bubbles in the paint, right where the mirror housing meets the door - definitely rusting.
I ran round to the drivers side to find exactly the same thing - it looks like the mirrors have either been badly fitted (and damaged the paint), or the base part that sits on the door has rubbed into the paint and caused it to start to rust.
Anyone else have this problem? I know the ford rust warranty is only inside-out but this has obviously been caused by damage at manufacture or incorrectly fitted mirrors - I'm going to drop in on the dealer later today and see what they say - there's no way a 2 yr old car should be rusting already!