Styrene can smell "sweet.' What kind of resin did you use for your repair? If it was an "-ester" that could be it.
Also, polyester resin was used to build the trailer, and that can give off such a smell (uncatalyzed styrene, I think). Have you drilled holes recently?
And/or has the trailer heated up now compared to when you did the work?
Rotting core can also smell this way (if you have, say, a wooden core between layers of fiberglass); but it sounds like you don't have any of that.
Thanks for the hint, but I know there is no water in the door, so that's not it.
You may have hit the nail on the head. The new floor didn't have a smell - but I have cut more than a few holes from connectors, lights
etc. Also have drilled a lot of holes. Maybe I need to get back in there with the shop vac and see if I have missed so "dust".