Oops, that’s not grampa’s hand. Notice how his arm is straight vertically next to his body and the somehow stretches all the way above Obama’s shoulder. He’d have to have an extra elbow and extra arm length to accomplish that.
It purports to be. Here is a blow up.
Pic from Flickr site here , which has mouse-over notes on the irregularities. Anyone with a free Flickr account can add their own notes.