I'm with Bunny. I wash my hands all the time, because I'm sort of a health freak without actively thinking about it all the time. Also, I think working for many years in food service has made me develop this habit, because you have to wash your hands after everything. Itch your face -- wash your hands. Brush your bangs out of your eyes -- go wash your hands. Brush off your pants -- wash your hands.
It's like an instinct.