This reminds me of the TED talk about being wrong. It opens with the question "What does it feel like to be wrong?" And, of course, the answer is that it feels just like being right. It is only after you determine you are wrong, that you feel differently.
I think for a lot of people, positive and negative emotions are labelled according to what happens after them, or how the person thinks of themselves. We can be anxious or excited when we have the rush of adrenaline, we can feel sorrow or joy when something touches us deeply, we can experience contentment or boredom when we can find no motivation to act in any way, we can be passionate or angry when our blood rises, we can laugh uncontrollably when terrified or when deeply amused. They feel very much the same, until we think about what we are feeling, and give them a meaning. According to some standard theories of emotion (James-Lange and its refinements through to Gross and Barrett) they really are exactly the same until labelled. Then they are classified, and these reactions become part of our character. In the future, the same emotion is then going to be positive or negative according to its past consequences.
I think that only a few emotions are implicitly and completely positive or negative, and they are physical pain and pleasure and the strongly moral emotions of pride, belonging, guilt and shame. As the more ambivalent emotions get tied up with those, they become positive or negative in tone.
Nietzsche does a really good job of carefully describing positive moods: cheerfulness, gaiety, joy, clarity, excitement, contentment, happiness, ecstasy, etc. consistently enough that we realize they come in so many flavors that are well and truly distinct. So the culture as a whole gives us the tools to see this. But most of us seem to have a refined palette of negative feelings and a few strong positive ones, and they label only one or two of those as happiness, and pursue mainly that one. (This is one way of looking at the classical alchemy of humors: your balance of humors harmonizes with certain emotional states, that chooses what you consider happiness, and that defines your character for life. It is true enough in practice that it seemed like the best force of nature on which to base medicine for centuries. The precursor of Jung's theory of functions is the other way.)
To me this seems a waste. I think that we feel many flavors of happiness that go unlabeled, and pass as neutral or negative experiences, until we miss them, or we get a strong enough dose to find our addictions, or we finally see the good that comes of the different kinds of logic that the different emotions bias us toward.
So yes, I think it is probably the norm to not know most of the forms of happiness you actually experience, at least for the kinds of feeling that do not fit into your own self-image or character.