This is not a support request, just something weird that happened.

     I think that for just a frame or two my camera was displaced.  I was digging a tunnel downwards, and I was in the middle of some gravel... and my camera flickered.  For about a frame I saw a zombie right up in my face in the game.  I backed up, and it was gone.  I dug a little further, and there was no zombie behind any of the gravel.  I don't know what happened.  It was weird.