I'm playing the asteroid map (DA) against the Drengins Arceans and Yor. I'm kickin butt (beginner level because I'm pretty new to this game). I have 6 planets to the Arcean's 1 planet and my influence is really pushing in on him. Suddenly I hit end turn and his influence nearly doubles! It envelopes one of my planets and 2 of my morale mines. I planted a spy on their home planet to see what they might have built to do this but saw nothing out of the ordinary. Does anybody know what might have happened? Thanks in advance.

I'm going to build a bunch of fighters and take his planet by force now, but I really wasn't looking to have to resort to this in order to win.