Very similar thing happend to me recently. The next time, two days later, I refused to move. They wanted to take my 1B and move me to 5A (757). The FA got really cra**y with me. But ,the guy in 5B would not move either. They finally found a row where they could sit together. I don't mind moving for a "like" seat though. 4B to 5B for example (757). Although I always tell the FA's I moved so they can ask me for my meal first.