It depends how involved you wanna get with the inspection\repair. If there's mold under the paper that's gonna be dangerous and smelly eventually. You can take a razor knife, slice the bubbles and peer in and see what's what. If all looks good, take some wallpaper glue, smear on the backside of the paper and press\roll it back into place. I'd prolly go that route. Or, you can just bag it and use a hair drier and smooth the bubbles out and forget it. If you decide to open it up and find it's in need of plywood repair, your in for some major work and $$. Good luck.