Looks like a hand over O’s left shoulder, which is not in the pic without him.
I saw that hand. I horse around with Photoshop a bit and I was an art major. The guy who found this was right about the unnatural position of grandpas arm the the Obama photo. Look at the one with obama, Grandpas arm looks to be straight down along his side. It would be physically impossible for him to have his hand up on Obamas shoulder. That photoshop was amatuerish at best. It’s just that no one bothered to look.