"I thought maybe he was lonely and wanted to see some comedy. But he decided to get up and take some questions for about 20 minutes.
"It was up and down but ah, it was one of those things where it was like, why did that just happen? I guess he is Chevy Chase, he can get up and do that. But why did it happen?
"It was very bizarre. I was wandering around the back of the room going, 'What is happening right now? 75-year-old Chevy Chase is up there asking people to ask him questions.'"
Chase has a new Netflix film due out this year, The Last Laugh, where he plays a retired talent agent. He co-stars with Richard Dreyfuss and Andie MacDowell.
The veteran comedian formerly starred on hit sitcom Community but rumours circulated of him feuding with the series show runner Dan Harmon.
Harmon allegedly played a voice message from Chase at a wrap party, where he called the show a "mediocre sitcom".
Alison Brie, who starred on the show, said the incident was blown out of proportion.
The show runner was fired, but then after continued controversy Chase left and the show runner was reinstated.
Chase made controversial comments about Saturday Night Live last year to The Washington Post, telling a reporter, "I'm amazed that (SNL producer) Lorne (Michaels) has gone so low."
"That means a whole generation of sh*t heads laugh at the worst f***ing humour in the world."