Error or PMD?

Often times I run a coin with an oddity that's difficult to explain. Here's one that has me stumped- a 1908 D Barber Quarter graded AU 58 by PCGS:
What's caused this pierced eyebrow effect? Is it a planchet error? A struck-thru error? Or post mint damage? I'm guessing the graders noticed it and would have bagged the coin if it were PMD- but possibly not?
Any guesses?
I love them Barber Halves.....
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Comments
IMHO PMD some older coins have dings and such from being used as everyday money
39 packages sent and gotten safely
Damaged
Does look like post mint damage since several show upraised metal around the edges. But no idea of how it occurred. Nice photos.
I would call that PMD.... Until someone can convince me otherwise. Cheers, RickO
Here are a couple more shots of the same coin:


As can be seen in the extreme macro shot the surfaces of the depressed areas match the surfaces of the adjacent struck motif. If you've looked at a coin under a lot of magnification you'll know the struck surface on a coin isn't perfectly smooth; it has tiny bumps and ridges. It looks to me as tough the same bumps occur on the motif and the depressions.
I don't think the depressions are PMD; I believe they were struck into the coin.
PMD
The areas in red seem to be raised.
I would call it PMD.