After the incident, he apologised, explaining that it was all just a huge joke because he's a huge Bieber fan.
"What I said at the concert last night about Justin was meant to be a joke," he said on Twitter at the time. "However…That way it was said mid song did not sound like one. I am a massive @JustinBieber fan and I have nothing but great things to say about him and his music always."
Anyway... a year on and he's explaining the incident further.
In an interview on Dan Wootton's Bizarre Life podcast, he reveals that he regrets what he said, adding that he and Justin have made amends since.
"There might have been a lot of emotion that night, a lot of thoughts going through my head and maybe just, sort of, maybe I shouldn’t have said that," Charlie explained. "It’s not really fair to him."
Charlie continued: "We’ve come across each other since then and he posted that he liked my song 'Attention' on his Instagram, so we are good," he said.
Who knows, maybe it was all just something to do with Selena Gomez???