I was looking at a replay of my most recent game, and noticed one of the AIs doing something...odd.
It had a wormhole in the middle of its territory, and had sent a fleet through it to the other side of the solar system, fairly near the planets of the two other players it considered foes. The ships went from the far end of the wormhole to an adjacent (unoccupied, unoccupiable) system...then turned around and came back to the far end of the wormhole...then back to the unoccupied system...and so forth, a constant stream of ships moving back and forth.
I have a hard time thinking it was any sort of patrolling pattern; there wasn't really anything there for it to protect, and going back and forth like that would keep the antimatter reserves of its capital ship low. Plus, during this time, I was attacking it elsewhere, so presumably it would be trying to use those ships to defend itself.
It could, however, be a pathfinding issue - looking at the AI's tech tree, it seemed that it had gotten knocked down to 4 Civics labs, which presumably meant that while it had the jump-tech, that it couldn't use it (assuming it works like that; I know it does for, eg, Kodiak production) - and I could well imagine the distinction between "do I have this tech?" and "can I access this tech right now?" being the sort of thing which would cause strange behavior like this.
Or maybe it's just doing something infernally clever that I'm utterly missing. 
Anyone have any ideas?
--Eric
[Playing the demo version on a Random Medium map with Normal AIs, if that's relevant.]