Happened at a Neil Young concert I was at about 15 years ago. Loved his music, but had never had the opportunity to see him live so this was special. He was doing a mix of his newer songs and old and finally got to Heart of Gold, one of his best and a song everyone in the audience knew word for word. Could tell it wasn't perfect, but there were no complaints from the audience. Once he was done he announced he messed that one up and we deserved better, so he played it again to perfection. Very much appreciated that.