I looked at it this morning, and it's definitely vandalism. It looks like it was made by a chisel or like object. There is a gouge mark on the underlying plastic that peels in a downward stroke, and the damage to the red part of the taillight ends in a square section that would be about the right size and shape for a chisel. I'm wondering if someone took issue with my "Those who have abandonned their dreams will discourage yours" bumper sticker. Yeah, that could set off a lightly-balanced person of the abandonned dream persuasion.
Not the first time my car has been vandalized. Actually, I had the taillight covers *stolen* off a car, one night, at an apartment complex I lived in, in Campbell. (The cops shrugged and told me it happens all the time, and didn't want to take a report on it, sort of like bicycle theft.) And one night, my old Volvo had "satan" written across the trunk, while sitting in the driveway of my present house.
Oh well, could have been worse. Annoying, but not functionally a problem. As I say, it's not really noticable, doesn't affect the actual light part of the taillight, etc. Knowing what taillight assemblies cost (choke gasp), I will just live with it. Guess I won't have to wonder when I'll get the first ding on the car. :-(