Hmm, I've been playing for a couple weeks now and I havent seen this happen. Does the AI seek alliances to bolster it's strategy? I've never been approached by the AI with an offer, occassionally they'll give me gifts, but never enough to get our ratings close enough. Also, though I'm not sure it hasn't happen, I haven't noticed the AI allying with each other.
Anyone else's observations? I'm curious abou this.