But at one point, Obama paused abruptly after Roberts reversed several words in the oath.

The oath includes the phrase "that I will faithfully execute the office of president of the United States" but Roberts didn't say "faithfully" until after saying "president of the United States."

Obama apparently realized that something was out of order.

With Obama not reciting, Roberts then repeated the phrase correctly, the brief awkward moment ended and Obama was back on track.