I don't think she's actually ever said the thing about Tom Petty. Where that quote started to show up is after the Wiltern show and the Billboard reviewer wrote that she said that.
""For What It's Worth" was written about her summer riding the bus across the U.S. with Tom Petty and the Heartbreakers. (Heartbreaker guitarist Mike Campbell joined the band for the tune). Nicks called it "the best summer of my life-and you can interpret that any way you like.""
But she actually doesn't say that when she's talking during the show. She talks about becoming an Honorary Heartbreaker, bringing out a real Heartbreaker who helped her write it, and the song being about traveling across the country on tour in a bus and having the best summer of her life as a separate thought. The only time she's done that is on the Street Angel tour.
This new article, much like other journalistic endeavors that don't get an actual interview with Stevie, just regurgitate what they read in other articles (like Billboard).
The way Billboard layed out their sentence is wrong... She did say it was written about the 94 period... Billboard ran both that, and the fact that Mike Campbell From TP was there to perform it into one giant sentence... If they would have put a period after U.S.. Then it would have taken on a new meaning...