The bag I currently have seems to have dusty, almost sooty bits in it...? It doesn't bother the bunnies, but when I empty their trays its as if it has fallen to the bottom as it settles, and when I wipe the tray over it gathers on the cloth/kitchen roll... I'm not too fussed if it doesn't have a negative impact on the buns, but I did think it a bit weird. :?