I have a 97 monte carlo. Just got done washing my car and noticed paint bubbles down below the small door where you put gas in. It is in the area where the metal and plastic pieces meet. When you see paint that bubbles like this, it is almost certain that it is caused from the panel rusting through. Has anyone else on the forum seen this type of problem before? I now suspect that the lumina may also have this same problem being the same shape and design.

That could be caused by fuel being spilled onto the paint.

No, not caused from fuel. It is rusting from behind, a problem now becoming more and more common in Monte Carlos and Luminas. Don't even try to fix it by sanding and bondo-ing. It'll reappear in 6 months. 2 solutions: patch panel or filling the sanded rust cavity with lead and re-painting.