Some arfs use a type of film which does not shrink with heat, in fact the wrinkles get worse. I think its some sort of cheap vinyl covering. If the covering is the heat shrinkable type, then you can use a hairdryer, just gently heat over the affected area, let it cool and you're done. Just a note, a plane with a rougher finish seem to fly better than a smooth finish, ask the pattern guys. CPLR used brown paper on one of his pattern planes. So, don't worry too much about it unless the covering or trimming are peeling out !