Seated at a Mac laptop behind the scenes at the opening game of the World Series in St Louis, Michelle Obama typed her first “official” tweet as first lady and raised her arms over her head in victory after hitting “send.”

“Military families serve our nation too,” she wrote on the Twitter account of her military families initiative. “Let’s all show our appreciation by @JoiningForces with them.  Get involved: JoiningForces.gov  -mo.”

Her initials at the end “-mo” are to signify that Mrs. Obama typed and sent the message herself.

Her own Twitter news account, run by her staff, has posted a link to a video of Michelle Obama’s first Tweet  as she sent the military families message.

But it is not really the first time Mrs. Obama entered the Twitterverse.  As ABC’s Sunlen Miller reported last May, Mrs. Obama was seated at the head table of the White House Correspondents’ Association dinner, awaiting remarks by her husband and comedian Jay Leno, when reporter Ed Henry, then of CNN, asked Mrs. Obama to send a tweet on his iPhone.

She did, writing:  “from flotus: ‘here at dinner this is officially my first Tweet. i am looking forward to some good laughs from the potus and jay.”