I have this Bicentennial Kennedy Half Dollar with something strange on the reverse. It seems that the "F" in "HALF DOLLAR" is missing. You can see some artifacts of the "F", but for the most part it is gone. To me it looks like post mint damage (perhaps even done on purpose), but I would like your opinions. Maybe this is actually some sort of error? It also looks like the "CE" in "INDEPENDENCE HALL" is worn down.