So what??
LOL, never mind.
I do have to say though that you stated you've worked with PS for 20 years and didn't catch the light source........
Aside from the tone of the hand being darker than expected there is nothing unnatural about the light source. The image remains too small to sufficiently tell.
And yeah, if I can avoid being too snarky, so what? What does a picture of Obama with his mother prove? By itself, nothing.
But if we prefer to take a more conspiratorial approach we could say it is clearly not Obama because a. he doesn't have his Panama hat on, or b. there are no golf clubs in the picture which would certainly be the case if he was on vacation in the days prior to Secret Service caddies when he would have had to carry them himself.
Rabbithole.