No...seriously...what is that going down the back of his neck...? You said "a reflection" to the same question from another...can't be both and don't think it's either...but what...? It's not at all on Kozmo70 coin photo...nice and clean...but yours looks like an unshaven hairline all the way down the back of his neck. ???
Take a Kennedy Uncirculated or Proof Half in your hand, and look. It is a reflection of part of the engraving of the coin. Don’t believe me? Try it.
I saw the flags in the motto in the first photos, pretty hard to miss the DDO. I think the coin was held back because of the matte looking finish, this is common when the luster isn't as brilliant as the normal proofs for the year.
Reminds me of this which I saw today. Your coin is much stronger IMHO. This guy is probably wishing he hadn't bothered getting it certified.
My only point was that PF luster and MS luster are two different looks. If your proof has the heavy radial lines like a MS coin would have then that is the reason for the lower grade.
It has typical proof luster, just as the MS coin has typical MS cartwheel luster. I am sorry that I was not clear. I still think the pictured coin is considerably undergraded. Apologize for the misunderstanding.
Just using @Marsden photo of a matte coin. Your coin has that white appearance rather than the reflective mirrored surface that is consistent with the usual photos of a proof. Sorry to use a 70 instead. The mirrored surfaces. And some refracted light.