Some folk really need to lighten up and accept not everyone is as perfect as them. Accept that she is from an era where comments like that were the norm. Sure, it was a mistimed, ill informed comment but clearly, there was no malice in it. On a plus side she inadvertently put all of the students at ease during a very tense situation, no doubt increasing their chances of a good mark!
My Granddad, God rest his soul, was as racist as they come. He meant no harm by it, didn't realise he was doing it but it was the accepted norm and despite trying to explain many times that it was no longer acceptable in modern society he would often blurt out some language that some people would deem 'uncomfortable'. He eventually got it so when an Asian doctor attended him on his death bed we were very proud when he refrained from having a 'Prince Phillip moment'.
I'm not condoning the examiners behaviour but we have to accept that racism, especially when committed by those from a totally different era, will not disappear overnight. Time, patience and an iota of understanding works better than constant chastisement by the Peter perfects of this world.