Provided they expand directly at other Civs, I agree. However, if they expand directly at you, that's a problem.
That being said, I think it's a perception bias. We notice it because it affects us. If they expanded towards another AI player, we wouldn't even grasp the significance of it.
I have seen the AI directly expand at other AI when they've got no human to pick on on a particular continent.
Having said that my response to the stock standard and flimsy "Firaxis just programmed the AI to be more unpredictably human, you're just not understanding the rationale" rationalisation that the fanboi's here seem to repeat adnauseam as a blind justification is much the same as it is in response to Tactical, Strategic and Diplomatic AI issues.... that being "No, they didn't, they simply designed all AI entities with a 'Mass-Face-Rape-the-Human' bias that was a feature of simple AI design approximately fifteen to twenty years ago when I was playing Civ 2, caused by a lack of resources during game development, resultant in a half-finished game."
The Civ franchise is supposed to be representative (and has always been marketed and conceptualised as representative) of a simulated history, thus a finely balanced equation between gameplay/fun and realism. The current AI as a result of the design decisions behind CiV essentially represents a departure from this long-standing concept, taking the game from a "realism/history strategy/simulation" to "turn based wargame".
As much as some detractors argue that the AI issues in CiV are irreconciliable, and that CiV is a sub-standard game (Which is a gross and ingenuous exaggeration), the fanboi's on here will likewise make an equally gross and ingenuous exaggeration that the game is now fine as is, and that disenfranchised fans are just butthurt because CiV isn't Civ 4.
Neither argument is accurate, and indeed misses the point that the reason why there has been so much controversy is not simply because of the differences between CiV and Civ4, but indeed because of the difference in approach and design of CiV compared to the gradual direction undertaken by every Civ iteration before that. Whilst there are plenty of Gen Y'ers kicking around who might not have hit puberty when Civ 2 was released, there are plenty here who have the breadth of experience and should know better.
TL;DR - OP, yes, the AI is Sh!t.