Look at what appears when you play around with the contrast, I always thought it looked like he was playing pocket pool!
I get a lot of my pieces from Mr. Oeming's art agent on E-bay, and I asked him to enquire about this piece for me. Turns out that yes, it is original to the artwork. Apparently early on, Mr. Oeming would put this kind of "Easter Egg" in the artwork as a private little joke to try and give Mr. Bendis a heart attack. Bendis asked Oeming to stop it finally after he pointed out that their private joke might not always be private. Guess he foresaw a time when some geek would paste it up all over his website. He he!