I watched the USMA graduation also.
I can't remember the first part, when the distinguished graduates, the First Captain, Class President, and Valedictorian received their diplomas.
But, when they started rapid firing the rest of the class up the two ramps, Obama stood in the background, behind the Superintendent and the Dean. Each cadet I saw saluted the Supe or the Dean (right or left side) and that salute was not returned. Rather, their diploma was handed to them and they were given a hand shake. Same routine as the cadets filed back toward Obama, who shook each cadets hand.