wileyc,
That's the question I keep asking myself. If it were a clogged/old die, it is amazing coincidence that this feature -- this key distinguishing feature -- is the only feature on the whole die that became clogged. The the top, right, bottom and left all of the features are plainly visible. That's what led me to wonder whether the change was intentional. Perhaps they intentionally plugged the die during the course of its use? But if so, why? Just thinking out loud . . . .