Okay, that's comforting, thanks all.

The other dragon encounters I had were all "normal". The one other weird thing that happened is that I suddenly found a dragon skeleton directly outside Whiterun (almost at the gate, on the ramp up). I didn't kill it, either. On top of that, it was empty and I'm relatively sure it had the name of the very first dragon that is encountered. And the bones twitched for a bit, for a minute or two. Other than that, I've not noticed anything weird in about 34 hours of playing this character.