I went on an offroading trip this last weekend and the the terrain was primarily mud and various pack of dirt. Now I am getting a sound in my rear drivers side drum it seems. It sounds like someone scuffing their shoe on rough pavement every now and then. I did not jump it or give any unusual jarring impact to the truck that I can recall. Would this just be crap that worked its way into the drum or should I be looking for something else. We gave it a good powerwashing yesterday but today after work I plan on taking the wheel off and seeing if I can see anything. Any ideas on what I should be looking for?