Personally I don't think you tightened the stem enough. I'm assuming that this Nitto (Techtronic?) stem is for a threaded headset. Also make sure you have the right size.

But you might as well pull the stem out and put thin layer of grease on the stem shaft that will be inside the fork column, the wedge itself including the slope area, the threads on which the wedge is fastened to, under the stem bolt head, AND on the inside of the headset where the stem will enter and all the way down inside the fork column to about the depth that the stem shaft will reach.

Reinstall but make sure the minimum insertion line does not stick out above the top of the headset.

Then torque the stem binder bolt to about 145 to 180 inch pounds if it's a steel bolt or 145 to a max of 150 inch pounds if it's a aluminum bolt.

Then test the tightness of the stem by placing the bike on the floor and put the front wheel between your legs and tightly holding the wheel try twisting the bars side to side with about 40 pounds of pressure. If the bar doesn't move then it's tightened right. If it does move then retorque adding another 5 inch pounds and retest.

If this is the Techtronic stem the longer stem may have some noise due to the extra length of the stem that other stems don't have. Mine made that same noise until I went 5 inch pounds over the standard torque rating that most stems require.