Steelers Center Question

[simpson]

Not that it has a material effect on the game or anything, but I noticed during the Pittsburgh - KC game on Sunday that Pittsburgh's Center turns the ball horizontal to the line of scrimmage prior to snapping it.

This is something I've seen in pee-wee football games, and which is always immediately corrected.

I'm wondering if anyone else has noticed it. Any Steeler fans here? Why does the NFL lets him do it? Personally, I'd think the NFL would want to stop it just because it looks so bad. Is this legal in the NFL? Does he gain an advantage by doing it? (Maybe a quicker snap or fewer missed exchanges)