Wilsons Sandbox

I went outside today to investigate the possibility of a PVC storage tube in a similar position opposite the exhaust, and I noticed the rear fender had a decent amount of plastic scratched up. It only hit on the left side (opposite the exhaust). Probably an inch up on the plastic. Anyone else have experience with this? The fender had a good deal of freeplay in it, but from what I could tell was mounted at all the positions it had holes. Not a big deal, just curious. Andrew