It's an issue at the Dulles chargers and has been raised before. Part of the problem is that the EV charging spots in the daily garage are right next to the handicapped spots and the entrance to the terminal. Lots of cars park there (or try to) for convenience. Normally half of the cars in the spots aren't even plugged in, they are just parking there because they are EV cars. I personally am shocked at how many Teslas grab these spots. As others have said, with our range, we don't need it (I accept that there is likely the occasional person who drives to Dulles from Charlottesville or some other great distance, but I believe most of the cars are from within 50 miles of the airport). I agree that it is rude to hog these chargers when there are cars like leafs that have a valid need an very well need a full charge to get home.
Personally I think Dulles screwed this up. They should have put the EV chargers in the garage at the far corner away from the airport. That removes any incentive to park there for convenience. You park there because you NEED the electricity charge. I know a guy on the WMAA board and am actually going to bring this up with him the next time I see him.
All that said, yes it's a pain that your car got unplugged, but given the fact that you live in Ashburn and were only gone 3 days, I don't see why you used the spot to begin with. By way of reference, I'm on the road (international travel) 2-3 weeks a month so my Tesla probably spends an average of 20 days a month at Dulles. I normally charge up at home to 60% and park in Daily garage 1 (less crowded and I think more convenient since they have reopened the underground walkway from the garage to the terminal now that the metro construction is basically done). I've been gone for as many as three weeks and never returned to find my car with less than a 40% charge (and generally more like 50%) with no issues getting home. It's one of the big advantages of our Teslas -- the unbelievable range compared to lesser electrics. I will use one if I need it, but otherwise I just don't use them and leave them for cars who do (in the hope that when I DO need one, someone else will have been as courteous to me).