I'm having the exact same issue. The friction in the freehub is such that the pedals will spin forward when the rear wheel is spun (with bike on a stand) and if you attempt to pedal backward the chain will go slack and slap against the chainstay. My working theory is that the bushing has worn down after about 5000 miles so that when the quick release is tightened the face of the three-pawl freehub rubs against the inner wall of the spinning hub body driving the freehub forward when the wheel is spinning. The wheel bearings are pretty new (less than 2000 miles) and the freehub bearings really don't take that much load so I doubt it's either of those. The fact that the issue only happens when the QR is tightened points to some spacing issue in the axial direction (perpendicular to the motion of the bike). I've ordered a new bushing. I'll post back if that fixes it.
