My dealer, Ted Britt Chevy in Sterling, VA, fixed the issue I was having, but I'm not sure it's the same as that reported by others in this thread. For me, the driver's door panel was a little loose, right where you'd rest your arm out the window. I demonstrated to them that it had more play than the other side, and that it made obnoxious clicking noises. Their tech reproduced, and they ordered a replacement panel under warranty! Sound is now gone.