Happened to me a couple times in the last few months on the 8pm DFW-LAX. The airplane and crew come in from ORD on a 5pm departure and whenever WX or MX delays that flight it is a ripple effect. I have seen updates stating the LAX flight will leave as late as 1am when they can't predict how long it will take for the aircraft to leave ORD. Within 30 minutes of the delay notice it will go back to a near on-time departure if they decide to swap an aircraft scheduled for another route from DFW.