The Minnesota congresswoman received a personal letter from NBC’s vice president for late night programming, Doug Vaughan, a day after she appeared on the show. As Bachmann walked onstage, the show’s band had played a snippet of a 1985 Fishbone song entitled “Lyin’ Ass B—-.”

Vaughan wrote that the incident was “not only unfortunate but also unacceptable,” Bachmann spokeswoman Alice Stewart told The Associated Press. She said Vaughn offered his sincerest apologies and said the band had been “severely reprimanded.”

Fallon also apologized to Bachmann when they spoke earlier Wednesday, she said. He’d tweeted earlier, saying he was “so sorry about the intro mess.”

“He was extremely nice and friendly and offered his apology, and she accepted it,” Stewart said, adding that the comedian said he was unaware the band planned to play the song. “It’s just unfortunate that someone had to do something so disrespectful.”