The re-oathing took place in the Map Room of the White House.
The unusual step came after Roberts flubbed the oath a bit on Tuesday, causing Obama to repeat the wording differently than as prescribed in the Constitution, notes the AP.
The White House released this statement from White House Counsel Greg Craig:
"We believe that the oath of office was administered effectively and that the President was sworn in appropriately yesterday. But the oath appears in the Constitution itself. And out of an abundance of caution, because there was one word out of sequence, Chief Justice Roberts administered the oath a second time."
The chief justice and the president handled the matter privately in the Map Room on Wednesday night, says Knoller.