I am surprised you would say that. From what I've seen (I've followed him and other candidates a lot during the debates) he showed extreme self control, more so than any other candidate.

I tend to agree with the New York Times:

In the way Mr. Obama has trained himself for competition, he can sometimes seem as much athlete as politician. Even before he entered public life, he began honing not only his political skills, but also his mental and emotional ones. He developed a self-discipline so complete, friends and aides say, that he has established dominion over not only what he does but also how he feels. He does not easily exult, despair or anger: to do so would be an indulgence, a distraction from his goals. Instead, they say, he separates himself from the moment and assesses.

What were some examples of those numerous occasions where he's lost his temper?