Yeah I've had this happen too. Worse than that, I get players who adopt a condescending, superior tone, and tell me that I made a grave mistake in stabbing them, and if I were any kind of a diplomacy player at all, I'd see that my only chance for victory as Turkey, was to make sure that they, Austria, stay alive for the entire game, and that the real key to a Turkish victory is to capture Scandinavia and Liverpool, but that I'm clearly much to narrow minded and limited in my thinking to see this glaringly obvious possibility.
Oddly these sorts of players always have fewer than 5 games on their record here at webdip, but even though they're new to the site they're veteran players, who've been playing face to face games for 40 years. However, in spite of this extensive experience, they make the bizarre, and unpredictable moves more typical of new players, have no concept of how to actually talk to someone in order to get them to do what you want, and often even fail to correctly count the number of supply centres a certain set of moves would gain someone. And this has happened in nearly exactly the same way at least 3 times.