Like the initials on Kennedy's, its a common area for coin grease to accumulate and fill in. When I was a kid I used to go through and sort out interesting little coins like this. It would make an interesting area to study and put together a BU set of these. I would bet one mint did a better job of removing the grease than another, etc etc.
thanks. Can you believe I found this one, the 2012, the 2009, a very prominent 1987 BIE, the 1986, and a couple of lesser but still ineresting ones all in the same roll...
