I think part of the question is are they ready to “date” for marriage. If the answer is no, then you should definately say something to your parents.
If yes, what are your concerns? That it’s not tachlis, that you don’t approve of her for him or that you think they might step over the line of appropriateness? How frum is he? if he’s not yeshivish you may not be able to hold him to those standards. If he is, talk to him. Tell him your concerns, if you think he’ll listen. If not, consult with a rav before talking to your parents. You need to know from a religious standpoint what you should be doing (and not doing, so as not to break up a potential shidduch). I would talk to your parents only after talking to a rav.