Tough to tell from the pic, but the hair looks to be in reasonably good shape (little wear), so it may be a greased die... If it were a weak strike, I would expect similar weakness in the other areas, unless the coin is noticeably thinner near the error...
I'd keep it, it only cost you 50 cents. I have a collection of about 30 greased dies that I figured I might be able to sell at a later date as a lot. I like finding them since they don't come up too often.