Would be grateful for any advice regarding the plastic strip that covers the joint between the roof and the sides of the motorhome. Its about 4 inches down the side. While cleaning the roof I noticed that in places there was a small gap between the trim and the roof section. Is the trim just cosmetic or is it part of the seal between the panels. I cannot see any evidence of water ingress inside the lockers or ceiling and a damp meter readings are less than 5%. in those areas. Any advice welcome.