Lefty
I never knew Obama was a fellow left-hander. Looking at this, he's really a left-hander, with that deformed way of writing we tend to have. It's to keep from smearing what you've just written in dragging your hand over it. (Think about it: Right-handers don't have that problem.) And when you're signing a book that's going to be a keepsake, you want to be especially careful about that. So, yeah, I recognize this posture, and it's about as uncomfortable as it looks.