I have a 2008 Sundance 3300SK 5th wheel. It has 3 slides and on the Sofa and Dining Room slide I have a bow or wave in the gelcoat on the slideout about a foot under the middle of the window. I have checked to see if the wall or floor is wet under this area on the inside and it is dry. I bought the trailer a year ago and the previous owner said it has been that way for some time. The wave is about 2' vertically and about 10" wide. Any ideas on what could cause this or appx. cost to repair.