Really? In that case the text that appears at the top needs to be fixed to account for that. It said something like " has declared independence", although I might have the phrasing wrong. Also, I didn't even realise it had happened for a couple of turns because there was no message asking if I wanted to let them stay free (or to declare war). I thought it had happened to someone else. I had previously thought that independent cities could only come from your civ if you let them go through the domestic advisor or in complete civil war.