The first lady took on Fallon in a fitness contest last February on his show that included push-ups, a tug-of-war, hula hooping, dodge ball and a sack race.

Michelle ObamaMichelle ObamaMichelle Obama surprises Chance the Rapper with BET Awards video Michelle Obama holds fitness 'bootcamps' for friends Obama marks Father’s Day: ‘I'm most proud to be Sasha and Malia's dad’ MORE won and Fallon asked for a rematch that has yet to take place.

Fallon had not responded to the first lady’s tweet by post time, but he did thank his Twitter followers for the birthday wishes.

The actor, comedian, and late night host turned 38.

The "-mo" on Obama's tweet indicates the first lady sent it herself.