I have always said black, even my black friend asked me to describe another girl and she asked me if she was black? so I don't really see the big deal?
Not really. It would be unfair if it was considered offensive. I'm white, and if a black person called me "white", there would be no reason for me to get offended. So, if a black person is called "black", then it should be okay, unless they specifically prefer to be called an African American.
I've always called myself and others black. I almost never say African American. I think it should be done away with tbh. If it's justifiable to call all black people African American then why don't we call white people European Americans? AA is just a silly term for me, as are a lot of race labels
If a white person called me Black, I'd be perfectly fine with it. In fact, most of the white people around me say "Black". 
I probably could handle that.
AA is just a silly term for me, as are a lot of race labels