They asked him about his "top 5 in the world" comment they aired earlier in the day and he didn't back down from it. He thinks he's really really good, and it don't see a problem with it, because he is. Also, guys go the other way and say too much self deprecating stuff and we blast them for being phony. They can't win.
That's it? Wow. I don't think that's arrogant. Confidence is key, I think.
Side note: I went to college with this guy for a semester when I was a freshman. The Augusta State (now Georgia Regents) home course is right across the street from the campus apartments, and I'd see him every now and then when I'd go over to play. Pretty cool to see him winning on Tour now.