Hi, I/we have the same situation with the front rock guards; we bought our trailer new in 2002 and it was/is that way....gaps.
Leaves, needles, dirt, all get in between where the rubber gasket does not seal with the trailer's windows. I took this to be "normal" and never did complain to Dillons in Apache Junction
In the last couple of years I have had the problem of the rubber round seal coming loose at the corners....like it shrinked. By the by, I am still getting pieces of paper out from between the aluminium frames and the dark plastic.....think the paper was used in transit from Jackson Center to Phoenix, most probably.
I am afraid to bend anything--like the hinges on the corner rock guards--for fear the "fix" will be worse than leaving it alone.