I ended up w/ a sz 15 pair (I wear sz. 10) during a Nike Vault raffle. So, I obviously kept them DS. I pulled them out recently to get them signed, and they were yellowing too. I even had them in a ziplock and hidden away in a closet. But, still had some yellowing.
Summa Time in the LBC.... Copped from Proper. I still have a pic of me rocking these in my elementary school days (also in the LBC)... talk about full circle
I checked that seller thru your link. In the autograph game, COAs don't mean much... unless they're Upper Deck. Some bootleg stuff gets by PSA/DNA, which is why ppl take that authenticity w/ a grain of salt. Just like the last dude mentioned, anyone can make a COA like the one that seller...