Weird Bug Puts Homeworld in Fleet

I sent in a save of this last night. I had been fiddling with a few transports while the turn was processing, and when it finished, Dratha had completed a transport. It jumped to the planet, and the planet was shown (at the bottom, the map displayed properly) as a fleet icon with one of my freighters as the other choice. The freighter was one of the ones generated by the game to run a trade route, and it must have hit Dratha just as the transport was finished. I could not put Dratha in the fleet, but I could not access the world to launch the transport. All other worlds that completed ships that turn were fine. Dratha was stuck like this until it finished a second ship.

I know this explanation is a bit convoluted, but has anyone seen anything like that?