Agree - you book Premium class reward seats way in advance - so you need to watch the reservation - maybe once or twice a week. Things change.
AA reward with coach on AS. AA system doesn't know to rebook you if a new aircraft offers higher class of service.
I just had future travel on QF to AA. The QF flight schedule got changed - to 3 hours later. My connecting AA flight was now departing before the arrival of the QF flight. I had to call, and tell the agent to put me on the next AA flights.
If you notice a change to your flights - prep in advance before you call - to know what you want. Having Expertflyer is good for this.