Yeah, that sounds like graniosity to me. When I'm up I feel like I can do anything. I'm the greatest writer that ever lived. I'm the greatest singer that ever lived. I could not only graduate with honors from any course of study put forth to me, but in less time than it would take another person. How dare someone point out if I make a mistake, because I do not make mistakes. That person must be wrong. I am the best, and all others should see that I'm the best and folllow me without question.

It's so oposite how I normally feel. I normally feel I'm pretty average or if I'm depressed I feel like a complete loser. So, that's how I know it's grandiosity.

edit:
Also, if you ever watch the show "The Big Bang Theory," Sheldon suffers from grandiosity to the extreme. LOL.