From Slashdot's questions for the 2004 candidates:
Q: [snip]...changing opinion[s] due to thoughtful reconsideration ought not to be derided as flip-flopping. Tell us about a time when you had an honest change of opinion on a topic of national importance.
Nader:When I first arrived in Washington, DC, one of my first meals was a hot dog. After I discovered what were in hot dogs I never ate another one. I changed my mind.
Kerry: If the leaders get the facts wrong then they should admit it. If leaders form their opinions based on a set of facts and they learn that those facts are wrong, it is appropriate to change their position.
Bush: President Bush declined to answer this question. - Editor
No candidate answered the question directly or particularly well and that sucks. However, Bush's reluctance to cop to any failures at all and to not even attempt to address this issue is both troubling and telling.
If I had to answer for Bush, I would have brought up his post-9/11 pretzel choking incident to counter the strong Nader-Hot Dog parry.
"Next time, I'm sticking with chips!"
update: A good reason to learn Flash
