I don't think you jumped the gun at all. Appears that they are not even selling seats on that DL2014 flight. If they force you to a different flight time, you can request a refund since it would be a 2 hour schedule change.
It'll be interesting to see if they even sell tickets on the last two DC9 flights to the public -- they show on my desktop schedule, but not as being available for purchase on line -- the other flights between the city pairs do show as being available.
Bob H