I'd never noticed this "feature" until the other night when I pulled out into a dark unlit lane and the high beam didn't flip up until I was going quite fast. I did think it was broken or just having a spaz

Does it really stop working altogether when sub 40mph or does it not initially start working until you hit 40mph then works at any speed depending on the amount of ambient light it can see?
Tweaking it down to 30mph would be a useful thing I think.