You've covered a third of the world in a half a week. That's plenty. There is no reason for you to prove that you have the energy of a sprinter.
But the fact is that you stumbled when you met with diplomats of the European Union and addressed 500 students at the European Parliament. The diplomats were, well, diplomatic and, what's more, happy to see you. Happier certainly than when they had to encounter Condi Rice who, if truth be told, knew only a bit more than her boss, which is not a lot.
Reuters reports on your missteps today. They aren't serious. But they are embarrassing.