Saw dust or sand?

We just bought our second travel trailer and have only taken it out a couple of times. When I opened the door today to load up for our next adventure, there is this saw dust or sand like stuff all over the floor? (It is also on the bed above the vent)
I didn't notice this with the first camper. Does anyone know what is causing it and should I be concerned?
Pulling a 31 ft Wildcat with 2 slides.