Djlawman: This experience sort of shoots holes in my remarks on another thread, directed at you, about checking bags. However, in over thirty years of frequent flying, I've had only one bad baggage experience, when my bag went to the wrong carousel at DFW and it took an hour or so to find it. BTW: If my schedule has been messed up in any way and I'm late getting in, the first place I check is the bags lined up but unclaimed from earlier flights.
Another thought: NEVER ask the agent at your arrival gate about when another flight will depart. I never even ask for a gate number. Just check the screen and go to the gate shown there (or to the airline's club if the screen says the flight is cancelled or delayed - assuming you're a member of the club; if you're not, take your chances).
The situation you describe seems unusual for Delta. Their agents meeting flights in CVG are looking at the same screen you see when you walk down the concourse. It could be that the agent you spoke to was looking at PDQ instead of PDX, and THAT flight had already departed. I have had situations where the information on the computers available in the Crown Room didn't match that on the screens in the terminal, but that's not what you ran into here. (The Crown Room info was almost always better)