Sometimes you can find it from Flight Stats - or if you get lucky and actually know someone who works for US (flight attendant), they can get to the bottom of it for you.
It often is very difficult to get to the 'truth' of the situation. Recently my plane was pulled from the runway before takeoff and given to another flight because that flight had experienced a bird strike on take-off. No one at the service desks and even initially at Customer Relations wanted to 'admit' that. It took a lot of digging, perserverance, and having a flight attendant friend who also did some investigating before the truth outed, so to speak.

According to the US Airways Contract of Carriage, "When a US Airways flight on which the customer is being transported is canceled or causes a missed connection, due to reasons within the control of US Airways..." there is usually some form of compensation offered. You just have to have your facts and not give up.