To those posters who are saying OP should have used Tiger Woods/TV 'opportunity' to try and explain PC etiquette to a tiny DC:
do you really think that a 3yo (or younger) would understand this and have the capacity to filter/censor what she says about the world around her in this way?
Actually yes, studies have shown that they do. By the age of two, children easily group based on colour and by three, they start attaching value judgement, based on family, environmental ,media messages.
In a fascinating study, black and white toddlers were shown pictures of children their age and asked which ones they 'liked'. Those under one, picked randomly. The toddlers aged two chose predominantly within their own racial group. At the age of three, both black and white toddlers chose predominantly white children.
It seems, the worst thing you can do is not talk about race with your kids or say "shhh", as if it is an embarrassing or a taboo subject.
What researchers recommend is having friends of different races so that children are exposed to this within their home environment
If that is not possible, when they are very young, introduce them to different races through dolls/books and emphasize how people are different from outside but the same inside.
From the age of 3 onwards, introduce the subject of inequality and racism and how this is something based in society and history, in age appropriate language. Children this age do seem to understand subtle messages of social hierarchy, and if parents don't discuss this openly, kids will absorb it from their environment. There is a fairly strong body of research supporting this approach.