Update: After trying to phone Delta all morning yesterday and getting a busy signal every time, I finally got through. And after being on hold and having to listen to Christmas music for twenty minutes, I finally got to speak to a real live human being but it did not begin very auspicously. I explained the situation and asked if I could change my outbound flight for the non-stop flight. He replied that there were only two buisness class seats on that flight. To which I replied: "that's fine, I only need two seats." He said that he would have to "clean up" my reservation before he could make the change. then, a long silence, punctuated by much huffing, puffing and other sounds of frustration. Finally he tells me that the system will not allow him to make the change but that he will make it work. He tells me to hold on while he goes to seek help. After being on hold for an hour he comes back and tells me the reason why he could not change my reservation: while he was working on it, Delta cancelled my return flight!!! However, all was not lost. He said that he could put us on the nonstop in business class, and asked us which flight we wanted, the morning, early afternoon or evening one. I was online checking FF availability while this was going on, and said I only saw the red eye. But he said that he could put us on one of the other nonstops although there was no FF seats because (and I love this part!): "it's our fault and we take responsibility."
So now we have nonstop flights in both directions. However, the flight is not until May, so I'm sure Delta will find a way screw up this reservation too. And to think, I could have gotten the AA nonostop flight in first class for the same amount of miles, but I wanted to use up the worthless Delta miles ...