sawdust

Ever since the Arizona Ash in the backyard was removed, Shawn has periodically been drilling holes in the stump in order to help along the decomposition. Today he drilled a couple of holes and of course the yellow/white sawdust came out the the holes. However in some weird chemical reaction, after about 5 minutes, the sawdust turned pink. Like REALLY pink. Anyone out there have any clue about why this is, or if they've ever heard of it?