I have a 7th Gen Accord Sedan and I have had this problem.
Call me crazy, but it was last summer when I had some bird droppings on my car.
Don't ask me why, but for about two weeks I was so busy with work and school, that I never got around to cleaning it.
When I tried to clean it, there was a rust circle under it. THAT'S ONE THING.
The other is I've noticed when I go through automatic car washes, I've seen some "paint streaks", meaning I can see the gray color of the steel under the paint job in small "streaks".
I've stopped getting my car cleaned in the automatic car wash (at many gas stations) and the streaking has stopped.
Just something to think about.
- HD