If you’re getting dust in the kitchen area, it very well could be a seal problem. We had the same thing with our 2004 3380. The factory guys fixed it.
We used to be able to see light if we bent over and looked under the stove, along the floor. We’d get muddy water on the kitchen floor after driving through the rain.
If you think it’s from the bottom of the slide, take a look at the bottom before you head out, and see if the black surface is covered with crud that could fall off onto the floor when it’s in and bouncing around on a trip.
I had a couple of photos of the muck on the floor on this PC, but now I can’t find them…That’s the problem with having way too many directories of photos, with several back-ups in other drives and locations, I guess.
But it might get worse than just dust coming in.
Steve
P.S.
Aha! Found said pics! Here's one: