i'm not going to tell anyone what is or isn't racist, in my opinion, that's up to/for each individual to decide. or how they want to define it.
i don't believe referring to white girls as becky is racist though. it is, however, racial stereotyping. and while this all may seem like a victimless crime, it shouldn't be excused.
personally, beyond her hit track, Single Ladies, i don't care what beyonce says or does or thinks. she's irrelevant to me.