Premonition has established itself among the solid lead US guilds before, having also been the first US guild to get Heroic: Alone in the Darkness by killing 25-man Yogg-Saron with no watchers. It looks like they're poised to continue that streak now that all the bosses in the Coliseum are unlocked. Congratulations to them, and good luck in the future!
Update: We're attempting to verify this through other means at the moment. Hold onto your pants! -Alex
Update #2: Confirmed.