Oh that, yeah that is completely normal. While locomoting / moving with a thumbstick you get put in to lock head. That's why it does that small movement in lock hip, but not while you are in lock head.

I assume that's done since while locomoting, your hip and legs are animated, so it uses the head for reference instead of the hip. Maybe while locomotion animations are disabled, it should stop switching to lock head and should just stay as is.