Mine is getting worse and it’s very frustrating – especially when you see Sierras and Silverados without this problem. Whenever I see someone’s 2014 or 2015 the first thing I do is check out the frame in the rear wheel well. I’ve contemplated taking it up with the dealer and bringing up the bulletin, but do I really want them taking off the box etc? I thought about giving the problem areas a shot of black Rustoleum or something, but this might make what’s left of the coating come off even faster. Hopefully this is just cosmetic. Regardless, it’s not a good feeling paying 50,000 for a vehicle and experiencing this issue on something that’s not even a year old. I guess it doesn’t hurt to try the dealer route and see what they say. In the meantime, have you thought about trying the plastic GM Wheel House Liners? I’m not sure if they go that far down to cover the frame but it might be worth it to look into..