It isn't one of the vagaries of air travel its one of the vagaries of shoddy IT! And why would the airline care about bumping another passenger when they clearly had no issue bumping the OP? It has been happening a lot lately - I had three bookings get the seats dumped all on the same day last week: 1 equipment change, 1 schedule change and 1 computer fart. I normally grumble and don't complain but I'm going to start.