Justin Bieber Mom Back in the Fold Front and Center at Concert

3/21/2016 7:04 AM PDT BY TMZ STAFF

0321-bieber-mom-concert-INSTAGRAM-04Justin Bieber's mom mysteriously reappeared in his life Sunday night ... showing up at his big L.A. concert.

Pattie Mallette has been "pretty non-existent" in Bieber's life ... so he says. That's why it was especially interesting she came to Staples Center and not only watched the show, but posed with Hailey Baldwin on Shots.

As for why their relationship was distant, Bieber has said he was ashamed at his conduct over the past few years and didn't want to face her.