How do you respond when a spouse displays negative character in front of kids?

On our way home from movie mat. today my husband made a very disparaging remark about a music instructor where my 9 year old takes lessons. Not my child's teacher, but could be in future... The remark that was made was very immature and totally the opposite of the type of behavior I would want my children to display; I want kids that are tolerant of others, open minded, fair, and kind towards people of diffrent backgrounds. My husbands comment I see as a huge character flaw, not the kind of thing I think an adult should model to a child, it pretty much ruined the outing. How would have you responded? I have known this man for 20 years, married 15.