Yes they can give you shit for that. Obstruction of the license plate. Same concept as a tinted cover, or even a “dealer” plate cover/ring thing.
Nothing is allowed to be affixed to or over the license plate.
Take a thin stripe of that reflective tape hell even 1/2" X 4" would do, and put it on the plate bracket, JUST above or bellow the plate itself. Then your legal.
Honestly chances are he got you primarilily for the mirrors, not the reflector… much easier to spot.