From Advent Children.net's translation of FF7AC Reunion's report of the Crisis Core trailer at the Tokyo Game Show:

[Scene with Zack running, holding a phone in one hand and his sword in the other, confronting Bahamut.]

Zack: "Aerith? I'll have to get back to you later. I've got a guest."

[Zack puts the phone into his pocket and readies his sword to face Bahamut.]

Zack: "I'll try to be a polite host."

It's official. Zack is made of win and awesome.