It is
Machine Doubling. The mint mark is pushed aside. Sometimes the mint mark is higher than the other devices on the die. Because the mint mark is added after the die is created, the mint mark is later added to the die. If it is taller, the
Machine Doubling after the strike can bounce touching just that area.
Machine Doubling doesn't follow rules. You can see different doubling difference between each strike:

These came out of the OBW roll and you can see the same markers on each coin. The
Machine Doubling varies on each strike. It just depends on how much play is in the machines setup. They can adjust it, and it will be fine again.