Well, I've had similar experiences in the past as well. However, mine has a little twist to it. Today's a good example. I used the E-ticket machine and was not upgraded (I am gold elite). The worst part was, the E-ticket machine did not even have my OnePass number! This is probably the reason why I wasn't upgraded. So, I go to the gate agent and asked her to print out a boarding pass. My OnePass number was printed on the boarding pass. Then when she checked the F inventory, F was available so I was upgraded. Not sure what the glitch was. I have not changed any part of my itinerary at all. Oh well-- I guess there are still glitches with those e-ticket machines.