1918-D Lincoln Cent - Possible RPM?

I'm not sure if this is something or nothing.

The coin is a VG+ 1918-D Lincoln, with a century of normal circulation dings. It is well struck, with a clear date and mm. It definitely is not RPM-001 or RPM-002. The mm is tilted fairly sharply to the NW, unlike either known RPM.

Here is the date and mint mark:


Here is a closeup of the date and mm:


Here are the details of the mm:


Here is what I see that makes me wonder about this mm:


There appears to be something SE of the mm, from 3 o'clock to 5 o'clock. The top serif could have a notch, or could have just a circulation ding. There appears to be something at the lower serif, as well. There is a weak vertical line inside the mm, and that definitely interests me. Whatever is at 5 o'clock on the mm is also very interesting.

I could see a NW-oriented tilted primary D over an upright secondary D here. Or I could see just a circulated coin with a meaningless, but obviously tilted, mm.

I have seen this mm before, on much more heavily circulated coins, and have paused a couple times when looking at it. The more worn coins, however, were too far gone to make me do more than just pause briefly.

Thoughts?