I have the same problem on my drivers side. I took it back to the dealer and they couldnt fix it. They test drove 2 other vehicles from the lot and had the same problem. I think it is a design flaw possibly from the mirrors. The dealership said I should contact GM but thats like fighting city hall. I guess if a lot of people complain to GM maybe they will realize the design flaw. Keep me posted if you come up with anything.
Mark in New Jersey