Sure is. In fact most bipolar people have great issues with coming to terms with the diagnosis. I was misdiagnosed with depression at first. When my pdoc noticed a drastic upswing in my moods and told me I had bipolar I was like hell no I don't. I abruptly stopped all meds thinking I was cured. It wasn't till I experienced my first full blown manic episode that I willingly took meds. For some people it takes years and multiple hospitilization so before they accept the diagnosis.

This is very normal. Just remember that this does NOT define you.