Light corrosion and a scratch through the tree. Just one of those might have been allowed to fly, but both not so much, maybe? Looking through other straight graded coins, I see more egregious scratches (https://www.pcgs.com/coinfacts/coin/1652-shilling-pine-tree-noe-29/892776), so maybe it came down to the mood of the graders.

I think they're thinking environmental like you mentioned, I always wondered why sometimes pcgs just says damage, and most of the time they classify the damage, I recently saw a draped bust dollar with the only possible damage being a fairly large scratch through the design on the obverse, I have no clue why they didn't just put "scratched... lol

I'm going thru recent small planchet sales and haven't seen a nicer struck coin in XF, let alone VF, straight graded or not. Other straight graded coins have similar pitting. Maybe because the grader wasn't Richard August or Chris Salmon? ;) I don't know if politics really matter or not but coins like this make me think...

I would agree with PCGS, registry collector, probably pitting from being in the ground

Pitting? Very nice coin though nonetheless.