I had the same problem and realized that the rear bumper actually touches the light. I was able to put a little piece of foam where it was touching and the squeek is gone.
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2009 370Z Magnetic Black/Persimmon|6MT|CNT CBE|K&N Typhoon|3M Tint|License Plate LED|GTR Start Button|PlastiDip Handles|180* Headlights
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