On my first round of playing, I was Rebels and went against three hard AIs. In two separate instances I noticed one of them sending a capital ship, on it's own, to a planet that I was in the process of conquering with a massive fleet (Titan and 7 capital ships, as well as a lot of other ships), seeing the size of the forces, and turning around to leave, though sufficiently slowly that my fleet was still able to do damage...and then it came back and repeated the process, continuing to do so until I destroyed it. A few planets down the road, the same thing happened again, except there were apparently 4 different capital ships caught in the same loop, arriving, leaving, and returning until I left my titan there to destroy them. Not sure what could be causing it, but since it did allow me to take out 5 of their capital ships without much of a fight (not that they would have been much trouble anyways, dang that titan is AWESOME)  I don't think it is what was intended.