This is a little tough to answer in one way. Was he dishonest, or did he exaggerate (said he was almost 6′ tall when he is 5’9″, for example)? Did he say something dishonest about his work situation, chronic health issues (by omission), where he went to school? If it is a serious breach, yes, I would tell the shadchan, absolutely. If it is a naarish thing, so don’t go out with him if it bothers you, but don’t mess it up for him, either.
He may be embarrassed about something, like there is a divorce in his family, but that is not being dishonest, really, it it feeling uncomfortable about giving such details before he knows someone well. If he was MARRIED before and failed to disclose, that is a biggie.