I got a good "What!?!" moment for you. It's got to be a bug too. No pics or anything, but it's happened twice so I know it can be reproduced. Here goes....
I am playing as Russia, and move my spearman to the borders of a city state to steal a worker. I didn't know it at the time but Persia had declared to protect the CS. So my turn comes, I declare war and steal the CS's worker. Same turn I ask and get peace, and my free worker. Persia pops up saying how he doesn't like my agression blah blah, and I choose the nice answer, saying I'm sorry and will stop(I'm already at peace mind you), he says ok and he will be watching the situation closely. Next turn I move both my worker and spearman towards my lands, then my next turn Persia pops up again. Here is the "What!?!" moment. He says something along the lines of,"Your word can not be trusted. This is obvious because of your conquest of Catherine. Watch your back". I'm Catherine!!! I can't be conquering myself now, can I!?! I've had this happen twice, in two seperate games. I think he pops up the second time because I get a tresspassing for being in the CS borders between turns, but still he's mad because I'm lying and conquered Catherine? What!?!