I know any statement that starts "I'm not racist but..." is usually exactly that, but I find colour blind casting in period drama really distracting.
I've seen two films and a play in the last week where it's been really off - why go to all of the effort of period costume and make up, and then have really implausible actors?
Wicked little letters - first Asian police woman was 1970s. not 1920s
National Theatre production - 1930s play - white couple with an inexplicably Asian Child
Catherine Booth (co founder of Salvation Army) was not black
It's particularly jarring when they are supposed to be portraying real characters.
In contrast, I saw some contemporary dance/theatre this evening, I don't even race or gender of most of the dancers.