How did the humans of my home planet become Festrons??

I just noticed that ALL the citizens of my formerly human home world are now Festrons.  The Festron civilization is not even in the game. 

I am not disallowing foreign citizens on my planets.  There are a few Drengins and others on some worlds.  I guess the Festrons are like an "Invasion of the Body Snatchers" race that can turn other citizens into their own race, but, without checking all your planets every turn for a Festron "invasion", how can you know that a planet is infected.  I would think that the governor would notice and be suitably alarmed.  And, even if there was a notification, there should be some choice about how to stop it or let it continue.