I noticed something like this, though not the same, but might as well post it here instead of creating a new thread.
I faced Fire Queen with the recommended deck, then changed my deck to a PvP1 troll deck (unupped 'got poison?'), put my computer on hibernate and went to school. When I came home, I opened my laptop (the game session was the same) and clicked PvP1. I ended up facing some guy called Octane, with the recommended deck for Fire Queen I had used before. (unupped of course) I though maybe I hadn't changed my deck, or for some reason the game didn't save. So I quit because I knew I couldn't win with the deck. I then went to 'my deck', but it was the same as I had changed it to before school, the poison deck. I then faced AI3 to see if the deck problem was continuous. I had the poison deck, and won. Confused, I went back to PvP1 and found myself facing the rainbow AI3, the same deck I had faced just before. This time I managed to get a screenie:
Tl;dr, I changed my deck, played with my old deck in PvP1, played AI3 with my new deck, then faced it again in PvP1 this time with my old deck, but with my new mark.