The incident occurred yesterday at his solo concert, where he was introducing his next song, "Anthem".

"I wrote this song after I was inspired by Jang Bum Joon and his performance at a wedding, but I got attacked for copying him," he told the crowd. "That part in question is from the wedding march, so how could I be copying him? It's definitely my song."

"If you still feel uncomfortable, I'll mention Jang Bum Joon every time I play this song," he said.

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He went on to yell out his senior's name during the performance of his track. After a recording of his performance made their way around the Internet, gaining criticism in the process, he formally apologized for his behavior on Twitter.

"I apologize for causing a nuisance yesterday due to my rudeness," he said. "I, too, enjoy sunbaenim's music, and contrary to my intention, caused discomfort to his fans. I'll work hard to pay attention to my actions and words in the future."

What do you think, was an apology necessary?