Does seem like it was an option, even though not listed in the brochure as an option. But since there are 2 different rear view mirror part numbers that cover those years, seems it must have been an option. We’re the headlights set to “Auto” mode? That seems to be the two requirements. Possibly you may have to be going a certain speed and of course it has to be dark, with no headlights in view of the front of your vehicle.