Winnebago has an on going problem with rust that they address on a case by case basis. The topic appears in this forum now and then. Do a search on rust and you will find the posts. Bring it to their attention and have a factory rep inspect it look beyond the obvious in the photo there is probably more. You have a 50/50 chance at having it repaired at Winnies expense even though you are out of warranty.
07 Itasca Ellipse 40fd, 2014 Honda CRV, greyhound lab mix, pit pointer mix(RIP bessie) , shar pei mix, stupid cat, wife