PC going too far: Should we ban/change old rhymes in school in case they're offending anyone?

Some nursery rhymes such as the Baa Baa Black Sheep may be offensive, considered prejudice, and an unwelcomed reminder of racism in history. Though rainbow hardly makes any sense at all...no offense to Oxfordshire. I can understand if ppl find them a bit offensive, but i don't think they aredisturbing or bigoted. Then again, I have not read any nursery rhymns that are prejudice agains my own race, so what do i know.