So my chickens have a litter box under their roosts that is filled with sand. The rest of the area has wood shavings in it. I clean up the litter box about every other day. However, I found them recently dust bathing in their litter box. They have an area outside for dust bathing but if its too cold, they won't go outside. Is it ok if they do this? I imagine there's residual poop in their or sometimes if its a day that I'm not cleaning out the sandbox, I'd think there would be more.