It is very common to winnebago and is caused by how they make the roof. It must be checked about every 6 months and sealed if the edge is becoming exposed in any way. Winnebago is the only manufacturer to my knowledge that makes the roof the roof this way the fiber glass is very thin, forgot the thickness, that is secured in this manner. Don't think anything has changed since I owned any of the three winnebagos over the past years.the roof fiberglass coming loose is not covered under warrany. It is a maintenance item.