The paint seems to be peeling from my driver's side rear splashguard!!

Showed it to my dealer and they said it was caused by a rock, but there is no evidence of rock chip damage. Now, instead of a spot about a 1/4 inch in diameter, it has spread to about 2" long!!

Does anyone know if I can buy just the single splashguard pre-painted, or do I need to buy a new set of 4?? Surely I can buy just one from a body shop catalog.

Thanks for everyone's help!!

 

Why not just pull the one guard off and have the shop touch it up?
What could they possibly charge to spray one guard?