the good news is, we live in the 21st century! bipolar disorder can be treated! so if you really have it, you're tons luckier than your ancestors who had to suffer through people thinking that they have a nasty temper.
more good news: having occasional ups and downs is normal! you're alive, stuff happens to you, and you react. some of the reactions can be a bit too much, but you can learn to take control of them with time (though if they get out of hand on a regular basis, you do need to call the doc).
i'd say that if there's nothing distinctly stressful going on in your life, and if your ups don't make you roadrunner-style hyperactive, and your downs don't make you consider suicide, then there's nothing to worry about. it's wonderful that you are capable of realizing what you're feeling. knowing what's going on inside of you is the most important part of learning to control yourself, and, through that control, of becoming who you want to be.
