Are Minor Civilizations Supposed to Expand?

I know this was discussed in previous threads, and I thought it was decided that minor civs would not expand. I just started a B4 game, and by Aug. 2178, I ran into the Alexians who had two planets (so far) and two colony ships out of orbit. Is this just a test of the AI for B4, a bug or a feature? I have a screen capture PDF I can email if necessary.