Someone asked me about this. I don't know exactly why/how it happened.
It was a seizing battle, however the colony had no units on it so only 1 battle occurred.
[5:11:33 PM] Death 2: it was a fight for control
[5:11:39 PM] Kenny: Oh okay
[5:11:39 PM] Death 2: i asked the person who killed it
[5:11:45 PM] Death 2: he said he really lost exp
Strategy claims to have actually lost the EXP.