Melania Trump nudges Donald during White House Easter Egg Roll

As the national anthem played at the annual White House Easter Egg Roll, CNN reporter Daniella Diaz noticed something unusual.

Donald Trump and his wife Melania stood together with their son, Barron -- but at first, only two of them had their hands over their hearts.

Video shows Melania Trump subtly nudging her husband to remind him of the tradition. He quickly corrects himself.

Twitter erupted with opinions about the quick nudge. Most people criticized the president for not lifting his hand during the national anthem: