The mintmark was punched into the working die by hand until about 1990. You will probably find numerous examples with the mintmark placed in different locations. There are probably tens of thousands of Lincoln cents with this same placement. Don't start planning your retirement just yet. Chris
If they visibly ding the date they are worth a little more depending on the amount, but there are very few that qualify. Interesting in that other more valuable mistakes such as MM/Horizontal mint mark, wide separation of mm strike , are more difficult to recognize, such as this Where the mistake was mostly removed. 1956-D RPM-008. Jim