If you have the pinstripe I would do the whole gas cap cover. Remove the pinstripe then sand until smooth, don't have to go to bare metal if the existing paint is good. May have to do a bit more sanding in the affected area. Prime with an epoxy primer, let sit overnight just to cure and setup well. Wet sand, then do colour coat. Let sit for a few days to cure and harden, pinstripe, wet sand with 1000 grit then 2/3 coats of clear. If the clear/paint lifted then the adhesion let go and air got in underneath. No quick fix with this. Good project for the cold months - I'd wait until then. I'm still learning about this paint issue myself.