The 68-72 vette used aluminum rivets to hold the metal headlight support to a bonding strip,which in turn is glued to the under side of the nose. Over time the rivet corrrode and push up under the paint. Some have tried to grind them down ,fill and paint and they come back. Others drilled them out and had the same problem. It's like removign a luggage rack and filling the holes, the spot shrink and show over time. The best way to fix is to remove the support and bonding strip. Either find a NOs bonding strip or use a 73+ up support with 3M adhesive. I have the 3M part number if you want it. This is a big job though and requires a lot of disassembly up front and Hammering!! You have to be careful not to damage the glass in the nose. I would wait until you're going to paint the car to do this job.