I think the buyer should crack and resubmit, see if he can bump it to a 10
I'm not taken at all by the number, but do think it's cool when sequential cards meet again later in life. I got this Greenberg a few months ago... Ruffing just came and its s/n is 1 number higher. Guessing they may have been housemates prior to their being graded.
1939 Play Ball Hank Greenberg signed.jpg1933 Goudey Red Ruffing signed, previous eBay listing.jpg