Chris Rock walked off stage during his comedy set at billionaire Anthony Pratt’s Christmas party after making a controversial joke, leaving guests puzzled.

Chris Rock wasn’t mad when he walked off stage during a private comedy show, PEOPLE reports. “He didn’t storm off. He did stop performing, but he wasn’t angry,” a source told PEOPLE. “He simply put the mic down and walked away.”

The Post’s Cindy Adams, who attended the soirée, said Rock “saw something the audience did not” that “upset him.”