Am I being unreasonable with my in-laws? 10-points for best answer!?

I am in a mixed race marriage for over 17yrs now, and something still annoys the heck out of me. My in-laws who speak fluent English will sit and speak in their native tongue right in front of me. At their home...fine, I can understand that. But isn't it rude of them to do that in my home? Or when I'm driving them in my car somewhere? I've told my wife on several occasions that it bothers me and that I find it disrespectful. Is that improper etiquette?