First you might want to try a tooth pick on the base of the neck to see if that is clear grease on that area? That could cause the issue you are seeing. If that is not the problem, then it might be a die over polishing issue. The die may have have been been polished with the edge of the machine inside the deep recesses of the bust, leaving an edge around the head. They call this a halo. we can see this a lot on the larger coins dies. (Halves)
