Franklin Half Dollar Grading

I am working on completing an uncirculated Franklin half dollar set. I recently purchased a 1953S online which I thought would grade around MS63 judging by the photos. When I got the coin I noticed dark areas on the cheekbone, behind the eye, and top of head on Franklin's portrait. Similar, but smaller spots also on the high points of the bell. Depending upon the angle of the light source (fluorescent or LED) the dark areas seem to come and go. Someday I may get all my Franklins certified, but I am trying to assess a grade myself for the time being. I do have a few that I bought in slabs graded MS63 and MS64. I have looked at them and also at photos of coins graded by NGC and PCGS. Some of them have less luster than my coin and are graded MS64 - 65. I also compared to PCGS Photograde, one of their MS coins appears to have dark spots also, while their AU examples do not, and I cannot determine where they are seeing any wear on the AU coins. I am trying to determine if the dark areas are indeed from wear, or just rub marks from being in a plastic flip. I have had pretty good luck self-grading my other Franklins but this one has me stumped. I know this particular year/mm is known for weak strikes as evidenced by the high value for those with full bell lines. If the dark spots are wear, then this will definitely lower the grade to AU, but if they are rub marks, does that also lower the grade to AU?