Interesting terms of membership, but legally no weight if not posted. When I was there a yesterday I looked fairly carefully. I didn't see anything posted.
If you really want a reason to avoid costco this is probably more relevant, though if I'm honest I think the police went ballistic in response, and yet another "we investigated ourselves thoroughly and found we did nothing wrong."
http://www.wnd.com/2012/06/cops-gun-down-man-for-legally-carrying-firearm/
Thank you for this posting this article..... a real eye opening.