You don't have to be symptom-less to be good and have a fine life. If you're not doing anything harmful towards yourself or others (so, that includes things like overspending as that's harmful to your finances!) then you're totally fine. You don't have to always seem the exact same throughout the various episodes - you're allowed to be more chatty and socialable or sad and introverted. Any and all are fine.

It really just means that he is a potentially good friend to have if he brought it up and was cool with it. It shows that he's perceptive. When I'm in either depression or hypo, it's not super noticeable to other people because I have pretty good management over my behaviours (and they're not extreme episodes). But if someone is observant then they would be able to tell the difference. It doesn't mean that I've failed or that I'm not good just because someone's noticed. Hells, my students definitely notice when I'm in an up. They just don't know that's what it is