funky stripes on my sock...

OK- I've had this lovely Lorna's Laces self striping sock yarn for awhile. I finally got the chance to cast on. And now that I'm 1/2 way through my first sock I'm not loving the way that it's striping. It's soft and cozy. But there's a weird spiral on my sock...

What's going on here? I thought this yarn would make nice even stripes. I guess it looks OK. It's just not what I expected.