There is a colored distributor marking on the top edges of many comics from the 1970's. I agree, and that as its very common also.
I know warehouse guys in the NY area who bought pallets of these blue inked 20 centers books back in the 1970's, they were credited as not sold by a distributor. They bought them real cheap on the secondary market. I actually have bought long boxes of these types of books, and got the story straight from the guy who bought them in the 1970's.
The Ink on this particular comic is not a distributor stripe, that heavy blue ink indicates it was on the returns. Similar to cutting the top third of the comic off. CGC will kill the grade, so would I as its no better than a 4.0.
You can get 9.8's on distributor marks without a problem.