I took it in to re-do this rust today.
It was painted over once last year for smaller rust spots. This time, the spot got large and is
easily visible from the side bumper. Since I live in northern California, not New York State where you got heavy snow and use a lot of salt on the road in the winter time, and I hosed all the salt and dust off from our (once of twice every year) Lake Tahoe ski trips right after I got home, I don't understand how this could happen (for a $40K vehicle).
The service director asked the tech to see him to make sure they sand it off before they paint it again. I hope it works this time.