The question of it being racist is all down to whether it was a serious tribute or they were taking the piss. [though, if they were taking the piss, you then have to split it into what they were taking the piss of to determine if it's racist]
If you wanted to be extreme you could flip the argument around and say it's racist to not allow white people to 'dress up' as black people in order to pay tribute/show respect[or even if they just want to be black, I guess]. Same as it being apparently racist for me to call my homeboys niggaz[as in good friends, the same as any other black [gangsta] man does]