No, I think when you start taking their towns fast their military costs really put them in dire straights and they dont want to spend 1000 gold + inciting revolts. To me, they seem to prefer ninja actions (although they dont always make the best decisions on what to hit).I used to see that behavior in Empire - then the next turn they'd attack again and do the same thing, and then again, and again. I think it is a bug.
Has anyone ever seen the AI use a monk to cause a rebellion in your cities? I'm killing the AI I'm fighting now by going around and destabilizing the cities I haven't gotten around to attacking militarily yet, but I have yet to see him do the same, even though he has monks running around everywhere.