I painted my '56 Chevy about 2 years ago. Deployed for a year and when I got back I have a couple of areas with little bumps. I probably rushed the coats. The bubbles do not feel squishy or hollow. I did all the body and paint work myself (took it down to bare metal) and am sure it is not a rust issue.
Unfortunately, I think they are raised just a little too high to be able to sand flat and still have clear to polish, but I'm tempted to try. If I'm gonna have to sand it down and repaint it, I might as well try it first.
Any other suggestions on repair options without re-basing and re-clearing the entire panel??