I am not sure about the explanation above... (very creative) :sign2: I have noticed on my 66 that the high beam light comes on sometimes during low beam operation. I believe this is due to a grounding problem in the instrument cluster. I have not had the time to pursue this yet, but it may explain the light coming on.
For me at least for now untill I fix my cluster the Red high beam lite is the ONLY lite that works in my dash, I drive using the tach for a speedo really sucks, of course I guess I could just not drive in the dark and it wouldn't matter....