Dave Grohl has been asked before why he doesn't play any Nirvana songs at Foo Fighter concerts. He's said it's just emotionally to hard. At an event to promote his book ;The Storyteller' his memoirs, Dave picked up an acoustic guitar and broke into Nirvana's 'Smells Like Teen Spirit' . Maybe talking about his life has lessen the pain of losing Kurt Cobain. As a fan, I'm happy to see Dave reunite with his music. https://ultimateclassicrock.com/dave-grohl-plays-nirvana-foo-fighters-book-event/