I think that if you recognize it as a manic episode, you should say so. I don't think that seems too "expert-y". I can understand not wanting to come off as a know-it-all, but that's a pretty basic thing. Besides, it can show insight, and from my experience, that's a positive, and their reaction to it has been positive. I think it helps them to know how to approach your care when they are aware of your level of insight.