Crikey, where did that come from?

Every morning I use the wall mirror in the bathroom to check my eyebrows, pluck out the odd stray hair from top lip or chin, you know the kind of things. This morning, I flicked a long black hair away from my chin......but it didn't move. It had grown, apparently overnight. How do these things happen? Honestly, it was a good 2cms long, an inch in old money.