1891 CC Morgan That Came Back Details (Cleaned) Can You See It?

I can't see any issues from the pics. Are there any fine hairlines?

I pulled up the actual True View photos, and I think I see what PCGS noted. Check out these areas of the obverse:
There are parallel lines across UNUM. they are most visible on the first "U" and across the "UM" and the field to the left of those two letters. Similar lines can be seen across the "URI" of PLURIBUS. (On the reverse, the "TED" of UNITED has similar lines.)
There are multiple south-to-north parallel lines from the jaw to the hair immediately left of the ear. These are probably the most visible of the lines PCGS likely saw as evidence of cleaning.
There are light west-to-east lines across the raised field of LIBERTY

There are other places, but these give an idea of what PCGS saw. It appears to have had a light wiping, but one that lightly scratched the surfaces. Where these lines are visible across raised devices, they are evidence of a cleaning.

Back in the 1960s and early 1970s, many silver coins were cleaned with baking soda. Those cleanings left light scratches similar to what I am seeing on your coin. I don't know if that is what happened here, but it was fairly common back then.

Just some thoughts.

It's still a nice coin and has nice eye appeal.

Looks like a solid MS-64PL coin but I've been in your shoes Ben. I have several nice BU coins I thought were problem-free but when sent to PCGS they were flagged as details (cleaned). I've thought about breaking them out for submission to NGC but haven't done so yet.
If you take a shot with this coin please report back on the results.