Where abouts on the head is it coming from, the front, the back, the middle?
See if you can see a hole on the pic that it might be coming from.
I can't see anywhere that it might be leaking from as the oil holes aren't on the extractors side.
Make sure all of your oil plugs are done up and check for leaks from the cam cover, it might be dribbling down, but then it should be happening all the time.