The band released a statement on their website Sunday, saying that he was seeking help but did not get into specifics.
Reports said the band was asked to shave some time off their performance to make room for other acts -- Usher's show ran 25 minutes long -- which caused Armstrong to get a bit peeved.
"I'm not f***ing Justin Bieber, you mother****ers," he raged, dropping over twenty F-bombs over the minute and a half-long ordeal.
"I got one minute, one minute left.... Let me show you what one minute f***ing means," he said, before destroying his guitar on stage and eventually leaving with the rest of the band.
Green Day is set to release their latest studio album, "Uno," on Tuesday.
It wasn't clear how it would affect Green Day's upcoming tour, which is set to kick off in earnest November 26 in Seattle, though the band did say it "regretfully must postpone our upcoming promotional appearances."
Amstrong had also been slated to be a mentor on NBC's "The Voice."