Carbon steerer? If so, it seems that you have to crank down a bit harder on the top cap to preload the headset bearings than with alloy steerers. I had that issue, and another poster in the last few days also had it. Maybe the stem sticks to the carbon steerer? In any case, no movement is good movement. Should back off the cap just slightly after having it too tight. Loosen your stem bolts and crank down some more. Hope this helps.