My understanding is that there was the potential for the same paint material (slop red oxide for your year and assy plant most likely) used under the vehicle to have been applied to this area, but since it is at the tail end of the vehicle, I suspect that it would typically have little to in some cases no coverage. That would depend on when the spray was commanded to stop in relation to the vehicle position. The next opportunity would be when the valance panel was left hanging by two screws followed by body color. Some of the body color would be seen as overspray on the ends, since the panel was hanging, and through the backup light holes, and some as well across the bottom, but the latter would be diffused quite a bit due to downdraft. That is my understanding for the Mustang, which I think would apply to Shelby as well.