foam in rear trunk lid, any ideas? Options

[restore2seater]

I took the doors and both trunk lids from my car to Redi-Strip in Roselle Illinois a while back to have them dipped in thier alkaline solution. I called them today to see how the progress was going. The guy there told me that the parts were pretty much stripped but he asked me something that I wasn't sure of. He asked if the factory would have put any foam in the rear trunk lid. The alkaline solution wasn't getting rid of it and he was wondering what it was. I told him I didn't think the factory would spray any foam in that area and that the only place I knew of that they did was the body. At the rear of the quarter panel above the taillight area and where the recessed area was for the door handle.
The rear trunk lid had a spoiler on it that I removed before taking the parts to Redi-Strip. I thought maybe someone might have sprayed something in the channels at the back edge of the lid on the inside to help seal it up. Possibly to prevent rust or to help stiffen the lid. I really don't know any other reason why you would need anything in that area.
Does anyone know if that area would have had foam sprayed in from the factory or why anyone would want to spray it themselves? (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif)