Wrong belt fitted, poor quality or badly adjusted idler/tensioner, failing waterpump bearing, badly fitted cover.
Badly fitted auxillary belt, tension wrong, failing alternator/power steering pump, loads of possibilities.
Why have you waited this long to query it? If it was mine it would have been straight back to the garage.
Best get it checked, if the timing belt fails the repair will cost more than the car is worth.
cufc, August 2009