John Mayer threw on a black jacket and headed out for lunch at LA's Madeo yesterday. The singer's been keeping a relatively low profile the past few months with minimal blog posts and public appearances, but all of that is about to change with news that he's one of the many headlining acts expected to rock Las Vegas during September's IHeartRadio music festival. The two-day event will also bring out Coldplay, Lady Gaga, J Lo, Alicia Keys, Carrie Underwood, and Usher. It doesn't seem John will use the occasion to make a return to Twitter. The subject of not tweeting came up during John Mayer's speech at the Berklee College of Music recently. He said, "I realized about a year ago that I couldn't have a complete thought anymore, and I was a tweetaholic . . . I had four million Twitter followers, and I was always writing on it. And I stopped using Twitter as an outlet and I started using Twitter as the instrument to riff on, and it started to make my mind smaller and smaller and smaller. And I couldn't write a song." John ended his talk on a positive note. He told the students, "Anybody who's made it will tell you, you can make it. Anyone who hasn't made it will tell you, you can't."