Would This Be a Balk?

[Manny A]

Saw an interesting move by a pitcher in tonight's Reds/Braves game. Reds reliever Scott Sullivan, a RHP, was at the set position with R1. Sullivan would then look at R1 over his right shoulder instead of his left before pitching.

Now, if a pitcher turns a little while looking over his back shoulder like that, would it be considered a balk? I always thought that the reason we balk a pitcher for turning his front shoulder towards first is because this is considered a feint to first without throwing, a violation of OBR 8.05(b). But turning his back shoulder toward first isn't a natural move to throw to first, so this wouldn't be a feint, would it?

Or am I wrong in my understanding of the shoulder turn and why it is considered a balk?