Minor race makes comeback?

Hi all, I was wondering if anyone else has experienced this behavior, as I have experienced this in my most recent game. The I-League was at war with the Drengin, and were down to their final star system. The Drengin then invaded and conquered the I-League's last system, and I got the message that basically said the I-League is no longer present in the galaxy as they had succumbed to the Drengin Empire. A couple of turns later (3-5 turns or so,) one of my systems 'defected' to the I-League. Immediately, the Drengin raced to the system and invaded the planet. I again got the I-League is no longer present message. A few more turns later (closer to 10 turns this time,) another of my systems defected to the I-League. By this time, I was already at war with the Drengin to try and get back the first system that had defected to the I-League. While I was invading the first defecting system, I decided to take on the I-League myself. I was able to take back the system, and I again got the I-League has been defeated message, only this time it said that they had succumbed to the Terran Alliance (me). This was finally the last I saw of them in this particular game. Has anyone else experienced the minor races making a 'comeback' in this manner, when the minor race has already been conquered by a major race? Because of the planetary defections I experienced, I'm under the impression that perhaps the minor race either didn't get 'turned off' when it got wiped out by the Drengin, or that the minor race's influence remained in effect after they were wiped out. In either case, when I took it upon myself to eliminate them, once they were off the 'board', so to speak, they never made a return. Has anyone else encountered this?

Thanks in advance,
-GeorgeT