In this situation, I feel like you should definitely voice your opinion, but not in an angry way. Just tell her that it bothers you and why - be open and honest. And then hopefully she will reasure you that she is with YOU for a reason and that her ex is an ex for a reason. Since the relationship is so fresh, I think starting off with complete honesty is the best way! I can't imagine her getting upset when you are open and honest and not angry - if she does get defensive over that, then maybe you should suspect.