Since I started the 1.3 beta, it doesn't seem to matter how much another faction likes me, they will declare war on me at the drop of a hat.  It seems to be the running theme that factions with green smiley faces next to them in the power bar are the most likely factions to declare war on me.  They'll do this very early on, too.  Not much point in gaining favor with someone if it's meaningless.

Also, it's not that someone asked them to declare war on me.  They tell you when they do it for that reason.  They're just saying "We don't like you and are going to kill you now." or something. Or the one where they say they can't tolerate my actions anymore.  What actions?  You mean that Offer Tribute treaty we've had for a while?  It doesn't make any sense.  It used to be, if they liked me, they wouldn't declare war on me.