[BNW] Single Player: When do AI civs start the game hostile?

[Barking Iguana]

Most of the games I've played have been Deity. I don't recall anyone being hostile the moment I met them. Now I stepped down to Emperor to try different styles. I'm playing Zulu, which I sometimes have on Deity. I met Greece very early and they're immediately hostile.

Is this a Zulu thing? A Greece thing? A Zulu-Greece thing? Or an Emperor thing?

They do not covet my lands. They don't have any reason to dislike me that shows up when I hover over their icon in the upper right.