So I have one of the major races and one of the minor races paying me a weekly payment, for stuff we traded. On the diplomacy overview for those races when I click on them (the menu with the +'s and -'s), they show a + for "You are paying tribute" or something like that. However they are the ones that are paying me, I'm not paying them. And yes I have verified that I am not paying them anything and they are indeed paying me 
Obviously not a game breaker, just a little bug that makes the aliens like me a little more than they should.