Interior wall problem, New Photos

I had a huge setback yesterday. I went to put my roof panel in & notice that on of my interior side panels was not flat. After looking & measuring it I foud it wa bowed out 3/4" in a 18" wide area right in the middle of the wall. After scratching my head I start trying to pop the panel loose. That did not work. I ended up "breaking" it out piece by piece. At least I know the Titebond III works.
I had attached this piece in the garage & put a coat of tung oil on it before I stood the wall up on the trailer. The other side I installed in the trailer & is not oiled yet. The one with no oil looks fine. Any Ideas?
I had attached this piece in the garage & put a coat of tung oil on it before I stood the wall up on the trailer. The other side I installed in the trailer & is not oiled yet. The one with no oil looks fine. Any Ideas?