Shadow bug - Shows on trees in front of me

I was cutting down a tree, then turned around and saw that the shadows from the tree I had just cut down were appearing on the trees in front of me. Just watch the video and you should see what I am talking about:

http://www.youtube.com/watch?v=V9cYcElKPv0

shadows still have a lot of tweaking to do so this might be part of it.

I see this all the time but never in connection to a recently felled tree. Everywhere I go shadows move with the camera.