Mine definitely rocks gently on the yaw axis, but it can be ignored for LOS flying. The body of the plane follows a straight path and can be handled as such.
However I haven't put a camera on it yet, and for what was billed as an FPV wing, it might be really annoying.
I've read that yaw rock is an inherent flying wing problem though, so it's going to be interesting to try this big wing I'm building which has only the angled inner stabs.