I had the same issue with my 2000 SSEi. I thought it was because of the prior owner having a mask on the hood too long, but I found a GM TSB on the problem describing the paint adhession problem with the aluminum hood.
I had the hood repainted a few weeks ago and now it'* good as new.
BTW, I also had a corrosion (rust) problem around my gas cap. The paint was starting to bubble below the cap on the fender. I also had that fixed at the same time, but the body shop told me that it may come back and to keep an eye on it.