The fine was confirmed Wednesday by Reggie Roberts, the Falcons' vice president for communications.
Vick rushed for 166 yards in the 31-13 loss, just 7 yards short of his own NL records for a quarterback in a game. But that didn't make up for a dismal performance by the Falcons, who were booed loudly following their fourth straight loss and he showed his unhappiness by making the gesture with both hands.
Vick said he heard an especially disturbing insult from a male fan as he walked off the Georgia Dome field.
"He just said certain things I won't say in front of this camera," Vick said at a post-game news conference. "It was very inappropriate. I was down, upset, frustrated. I just did one thing I've never done through all the games I've ever lost, no matter how frustrated I've been after a game. I don't know where it came from, but the people who know me know that's not me and that's not my character."