I wouldn't say that it's odd. Maybe you had a sort of "medium-level" chronic type of depression? I have a friend who deals with this type of depression. He said he never realized until he was around 30 that he was depressed because he had always felt that way and considered it his normal personality.

So if that's the case for you, it makes total sense that it's going to feel odd when your "normal" mood changes. And you're going to be looking at learning new patterns of behavior and dealing with new emotions.