For anyone riding a Sigma X stem, did you torque the M6 socket screw that tightens your stem to your steerer tube to the recommended 15-18Nm as per TriRig? Seems like a lot of torque? Today was the first time I've ridden my bike outside and my stem got loose from only 5Nm of torque. I'm racing Oceanside Saturday, so anyones experience with this would be great.

I ride a 2009 P4 if it matters.