DD used to go to a multi-cultural secondary school.
She started sixth form at a CoE school that is probably 95% white British.
Tonight at parents evening a family arrived at the table next to us. They were Asian and the son and mum were wearing traditional Asian clothes. The teacher looked up and said to them. "Ooo, nice outfits. If I had known I would have worn my turban and head dress." 
I wish I had said something there and then but didn't
.
What should I do about it? Something? Nothing? WWYD?