According to diagnostic criteria, you must meet 3 of these symptoms (4 if the mood is only irritable), for at least 4 days:

-Inflated self-esteem or grandiosity
-Decreased need for sleep (e.g., feels rested after only 3 hours of sleep)
-More talkative than usual or pressure to keep talking
-Flight of ideas or subjective experience that thoughts are racing
-Distractibility (e.g., attention too easily drawn to unimportant or irrelevant external stimuli)
-Increase in goal-directed activity (either socially, at work or school, or sexually) or psychomotor agitation
-Excessive involvement in pleasurable activities that have a high potential for painful consequences (e.g., the person engages in unrestrained buying sprees, sexual indiscretions, or foolish business investments)

I think the tricky thing after being diagnosed with Bipolar Disorder is becoming paranoid about each and every small mood change, wondering if it could be hypomania/mania, or depression. Mood fluctuations are normal to a degree in humans, it need not always be an "episode".

Just keep an eye on things, but don't automatically assume it's hypomania if you are feeling a little bit more up than usual.