The Home Run Derby winner's wife, Kayla - among others - brought this to the internet's attention.
Much of the night felt like a send-off from Harper to the Nationals fans.
MLB How can I watch the Derby on TV?
Aguilar, whose 24 homers leads the National League, will join teammates Lorenzo Cain, Christian Yelich, Josh Hader and Jeremy Jeffress in the All-Star Game on Tuesday.
How can I stream the Derby online?
With 24 home runs this season, Aguilar was the top seed and faced Philadelphia Phillies slugger Rhys Hoskins in the opening round.
NEXT Trailer Previews Multiplayer, Space Fleets & Much More - No Man's Sky Videos
Invite your friends aboard and take on challenging multiplayer missions from the Galactic Commission Station on your bridge. Building bases will no longer be restricted to specific spots and players will be able to own more than one of them.
People should recognise that I'm one of the world's best'
French right-back Lilian Thuram scored his only two goals in a storied 142-cap global career in that semi-final 20 years ago. Croatia has a veteran roster that has been stretched to the limit but continues to win in Russian Federation .
French fans give hero welcome to 'Les Bleus' World Cup champions
Bottles were thrown, people shouted and booed angrily, before police finally broke up the crowd and forced them to disperse. Typically, celebrations in France end up with some broken shop windows and other destruction, and Sunday was no exception .
In the final, Schwarber came in just under his total from the semifinals with 18 homers and Harper started off his round slowly, but rallied late and got the tying homer with just a few seconds left.
Harper would go on to hit a HR Derby walk off with the title in his bonus 30-second round. Hoskins opened by blasting 20 homers, the highest number that had been hit to that point. He was greeted by a smattering of boos by Nationals fans but said he fed off the energy of the crowd.
Because we live in a world overwhelmed by a surprising amount of free time, there is already a Change.org petition to have Harper's victory taken away.
But on this night at least, Harper did not disappoint.
A few years ago Major League Baseball revamped the Home Run Derby format to make things more exciting and hey, it worked.
They will hope, however, that Monday night's festivities provide but a precursor to bigger things later in the year.