Oops, hadn't seen the other comments yet.
@Laguna, 2 jobs ago we had a folder for these kinds of mistakes the whole team could post to. I still remember from time to time. "That's one for the 'found' art folder". So I guess I'm more likely than the average person to save their mistakes now?
@toasty Various causes, I seem to remember:
Aww yeah! This is my kind of thread. I have a few of these actually, but here's one from before I added texturing:
Clearly I just needed to clear my buffer >_>.