The passenger had probably gotten tired of watching the meter turn at the long red light and decided to walk the rest of the way home. I've done that before. He apologized profusely, but I assured him it was I was fine and it wasn't a problem. They were probably exchanging money as I came up behind them, so they couldn't have seen me coming and the cab was too dark for me to see any activity inside, so it was just one of those things.
My hand hurt like hell for the next ten minutes of my ride, but yelling "Fuck!" over and over helped greatly and by the time I got home I barely noticed it. Fortunately, I was slowing to a stop prior to the collision, so my speed was pretty low.