paint bubbling on GM vans

I recently bought a 2000 Venture WB. In my search, I noticed that every GM van I looked at had paint bubbling along the underside of the rear edge of the hood, and also, the underside of the tailgate bottom edge. The tailgate I can understand, but why along the rear edge of the hood? Is this a rust problem or other issue? What is the recommended fix? I suspect this is a very common problem, but haven't noticed any postings about this (however just joined today).

Ask your dealer about Service Bulletin 01-08-51-004A/Peter in Sweden

Ask your dealer about Service Bulletin 01-08-51-004A/Peter in Sweden

Is anyone familiar with this bulletin?