Green Day lead singer Billie Joe Armstrong is seeking treatment for substance abuse after an outburst at the iHeartRadio festival in Las Vegas. During the band's Friday night performance, the singer began shouting on stage after the band was told it was time to finish their set. “I'm not fucking Justin Bieber, you motherfuckers! You've got to be fucking joking...I got one minute left,” he yelled. “Let me show you what one...minute means.” The band then went into a guitar-smashing rage before leaving the stage. Then yesterday, the band announced on their Facebook page that Armstrong is headed for rehab. “Billie Joe is seeking treatment for substance abuse,” the statement reads. “We would like everyone to know that our set was not cut short by Clear Channel and to apologize to those we offended at the iHeartRadio Festival in Las Vegas. We regretfully must postpone some of our upcoming promotional appearances.” About three weeks ago, Armstrong was hospitalized in Italy for severe dehydration, forcing the band to cancel their concert. But Armstrong recovered in time to perform at the MTV Music Video Awards on September 6. He was previously arrested for drinking and driving back in 2003. No details have been released about his addiction or how long he's planning to be in treatment. The band releases a new album tomorrow, but plans to postpone all public appearances until Armstrong returns.