Roof Molding

I was washing the trailer yesterday including the roof after a 5 day outing. On a ladder I was watching the water roll off the roof and noticed the roof molding where the tpo roof meets the side wall. The molding is what secures the tpo roof. I noticed where the edge of the molding meets the tpo material there is a slight edge. It seems like a good place for some sealant but there is none. I don't think it's a oversight I think they just don't seal it. Should it be?