It is a small date. The mark on the inside of the 6 could also be a die chip. Die chips happened a lot on this years coins, thus the replacement of the large date. But the key factor is the zero in the date.

Without this on your coin it would be a small over large date. The hubbing of the large date would have happened first. Then the hubbing of the small date next. This is just a small date and the large date hubbing didn't happen. So it is probably just a die chip.