Mike,
I have a similar problem showing up on the front curb side of my Bighorn. In the curve... under the bedroom part... the trim if flexing and showing a gap.
I've already added additional screws thinking the trim is causing this to happen. The screws did improve somewhat the condition... but it's still there. I was told by my dealer it was NOT a structure issue... I took that to mean it was not the Frame that was causing the problem... I feel it's the front aluminum structure that the fiberglass holds onto... I " THINK " there is a separation going on in that corner of the aluminum frame and the RV's steel frame structure.
One thing I did also note... I needed more screws than the factory installed on the angle steel inside the front storage compartment. I seen that area start to open wider... since I have installed additional screws in the existing holes on the angle steel... along the bottom front of the compartment... those screws have held tight.
Good Luck... If I learn any more... I'll post what I find out.