a k:
We run an 08, 4502 EX and although it might be different our slide DOES seal all around when out, including at the foot of those "columns". And....yes, where there IS kick molding at the base of a wall and floor corner, and where that molding approaches the verticle column when slide is extended, that molding does NOT extend behind those columns, rather the molding IS trimmed such that the slide columns (and the foam seal gasket behind and around the perimeter of the slide) DO firmly abut against the wall when the slide is fully extended.
If your trim (kick molding) extends behind those columns, I'm pretty sure it needs trimming to permit slide gasket to fully seal.
Don't know if this'll help....but, FWIW

Steve