Heres the photo. I think it most likely isn't (As something such as this would be most definitely recorded by now), but may ask well ask. Also, I have checked and it seems to be raised (Even if slightly.)
The mm’s were hand punched until 1989. To be misplaced to the opposite die, it would have had to be intentional. Looks like PMD from your pictures. The B has a mark on it also.
Ah, ok thanks! I had my dad look at it with a loop, and hes saying its a stain. So, thanks for the second opinion! It wouldn't be the most insane thing to be heard of in the world of errors.