He probably was confused when all of the sudden the band started playing My Country ‘Tis Of Thee.
I doubt he recognizes that, either.
Actually, that was "God Save the Queen", the national anthem of Great Britain.
As posted above/elsewhere, when toasts are being proposed, protocol states that the first one goes from the guest of honor to Her Majesty, and that it end with the words, "the Queen". At which the musicians are immediately to strike up the national anthem.
Obama blew a cue, through ignorance. Major, major protocol screwup. You do not blow your toast to the monarch.