It does have to do with the angle of the sun, and usually around this time of year is when everyone starts complaining that their headlights are too sensitive. The idea is that while it may be sunny in the open, it's likely too dark once you get into more shaded areas (think Manhattan, where the sun doesn't really shine between the buildings cuz it's too low this time of year). To prevent constant on/off cycling, the system keeps the lights on once a certain threshold is reached.
If it bothers y'all that much, simply manually turn it off until you want them back on. The system is working as designed.