Big Sean has a warning for Justin Bieber. During Ariana Grande’s “Honeymoon Tour” at L.A.’s Forum last night, the pop diva brought out Bieber to duet on “Love Me Harder” and “As Long As You Love Me.” But the Biebs got a little too hands on with Ariana during the flirty performance, which did not sit well with her boyfriend Big Sean.

Sean, who appears on “As Long As You Love Me,” tweeted (and later deleted), “This kid is about to learn not to touch my girl like that. Beliebe that.”

Bieber was seemingly unaware that he had upset Sean. After hitting the stage with Ariana, he tweeted, “Love the stage. Thanks for having me @ArianaGrande and thanks LA. Gotta tour again soon :)”

Watch the moment that had Sean heated.

UPDATE: False alarm. Big Sean’s rep tells TMZ that Sean’s threatening tweet is fake and he’s not upset at Bieber for getting flirty with his girlfriend. The two remain good friends.