Non-Kosher utensils

Question

If a non-kosher Jew prepared a kosher meal for you on his utensils, and they had not been used for 24 hours, can you eat the meal? Is this only after the fact? If so, let's say you know he is going to make a kosher meal for you, are you obligated to tell him that because of the utensils you won't be able to eat it? I realize that I cannot cook a kosher meal in non-kosher utensils, even if they haven't been used for 24 hours, but perhaps if someone else is doing it, I am not obligated to tell him not to do so (after all, he is going to be eating from the meal as well)