Welcome to the club. My roof is doing the same thing, only it is doing it along both sides of the motorhome from the front to the rear. I took mine to someone to look at it and they said there is nothing under the corner for the fiberglass to reattach to. They said there is a gap between the sidewall and the roof and the curved fiberglass covers this space. I was told National ran wires down this opening. I have the original brochures and one of them shows a picture of the wall to roof construction. And yep, the fiberglass bends over an empty space. Nothing underneath. I posted this concern in the past and several people responded saying their motohome is doing the same thing and they are not worried about it. However, I'm a little concerned and am carefull not to step or push too hard on the delaminated area. I plan on coating it with elastomeric RV roof coating and bought some elastomeric tape to repair any cracks that might develope. The right way to fix it is to remove the top side rails and reattach the fiberglass. I would never try it myself and I have not gotten a cost estimate. My guess is it would be very expensive. Let me know what you do.
2003 Dolphin L/X 6320