i would have been mortfied if any of mine did this, as my mum was when aged 3 my sister split her head open, we were on an RAF base at the time, so it was all white pretty much, but the duty dr who came to tape her head back together was black, very dark black. my little sister had never seen a black person before and she FROZE, literally which was good as it meant he could tape her head back to together easily! but when he had finished my sister piped up 'mummy can i eat the chocolate man now?' my mum was MORTIFIED and immediately apologised and explained to my sister that he just had different coloured skin etc. the dr was fine and explained it was because his parents were from africa etc.
it really doesnt take long to correct a child and had you started to do that immediately the lady probably wouldnt have been so offended.
interestingly on the way to toddlers today we saw a black teenager with a very big afro, we have seen him before and ds4 who is 3, commented on his big hair. i told him its not nice to talk about other people, but explained that yes he had very curly hair and had obviously grown it long like his elder brother but as it was curly it looked 'bigger' than his brothers who has straight her.
today we saw the young man again and ds4 said 'its the black boy wiht the big hair mummy' and AGAIN i told him its not nice to point and talk about people whilst explaining that all people are different with different coloured, eyes,skin, hair etc. ihave not used the word racist to him, as there is no need he is only 3, just explained that all people are different and its not nice to talk about peoples appearances whether that is their size, skin colour, hair etc. but children do observe differences and talk about them, esp when little.
my eldest went through a phase of saying that all the old ladies saw 'looked like a witch' again i was mortified and said its not a nice thing to say!! and apologise to the person that was in earshot.
so no your dd wasnt being racist but you shjould have immediately apologised and explained that it was not a nice comment to make.