Just picked up my truck from my local GM dealership to deal with the flaking undercoat/rust issue. Not only did they clean it and respray the entire underside of the truck, but they also re-sprayed the interior fabric protection as well. There was nothing wrong with this, but they decided to do it. Thought they handled this issue very well. They think the flaking/rusting may have started when someone put the truck on a hoist while the spray had initially just been applied; could have been at the dealership or factory, they don't know. Doesn't matter - They made things right!