I saw it on the news that night and was struck by how spontaneous and genuine his reaction seemed. Maybe it was planned and scripted, I don't know, but I doubt it (what would be the point?). I'm pretty sure it was his honest, off-the-cuff reaction to the face.
There's just something very right and cool about a president who reacts like that to an historical artifact.
And if you want to see a mathematical examination of the ET conspiracy behind Mr. Obama and the pyramids, check out the UFO ET Blog. It's all true, I'm sure!