Second guess was that it might have been that Russian meteor on its way.
Actually, that might be a good guess. Meteors/asteroids leave ionized tails, and given the closeness of the travel, it's possible that lots of ionized particles dropped into the ionosphere and upset the typical balance of stuff at that time of the morning. I guess we'll have to see if any of the propagation "experts" have anything to say about it. I did notice I had a bit of a glow when I got up that morning.