I've noticed often that civs get these suddent influence bonuses without a civ giving up and joining them. The influence borders even look screwy. Its like a sudden burst in their influence and it doesn't recede much if you use A LOT of influence space stations upgraded very high.
Also in playing one of these occasions I was frustrated so started anew. But for some reason I was told, when I tried to move my ships, that they were out of range and should set a course back to within my range. I couldn't activate auto-explore as well.
