We're assuming Mariah blanked one of her biggest fans by mistake given she happily posed with photos with Perry after the gig...


Anyway, here is the vid doing the rounds of Katy's left hand waving in a "hellew, it's me, hellew" fashion... She just didn't fall into Mariah's eye line, despite the massive fur boa. It happens. 

Since the encounter, Katy posted the below to her instagram with the cryptic caption: "MORTA :-( LINDA :-( " We have NO idea what it means, so it's best left open to interpretation.