I wouldn't trust anything they put on united.com. My wife was flying the other day COS-IAH and the plane was late. It posted late due to maintenance (which was accurate since it was COS Skywest maintenance base working on it overnight and not finishing up before the am flight).
Original delay...1 hour.....then end up finishing the plane early for a 30 minute delay instead. Shortly after takeoff united claimed the delay was "airport conditions preventing departure b.s."
The weather was perfect in COS and the plane was obviously late coming over from the maintenance hangar....gotta love them....