I idly looked aloft at the tricolor light, and it appeared to be showing its red light aft, which didn’t register as a problem, at least initially, until I looked aloft again and now saw the green light showing aft. It became obvious that the light fixture was unscrewing from the mast due to the movement of the boat as we sailed upwind plus the tapered threads used to attach the mounting post to the aluminum mast. I mulled over the possible explanations for a while, but what was exceedingly clear was the role of the tricolor light to my continued safety as I sailed amongst commercial traffic