[J.A.Sucker]

What's really happening is the field lines radiate out from the pair of magnets in a toroidal-like pattern. They go from one end to the other. If you spin it one way, you are starting momentum in this direction and are keying into the fields that have that handedness; if you spin it the other way, you key into the other field lines.

This is the answer, BTW, and would be easier to describe wtih a picture, but I'm not posting one.