From the AA website:
"In November 2010, Admirals Club launched an auto-renew program for new or renewal memberships purchased online at www.aa.com and paid with a credit or debit card. When you become a new member or renew your membership online, your membership will automatically renew each subsequent year for the renewal term and your credit/debit card on file will be charged the annual membership fee for such subsequent membership period unless you have opted-out of the automatic renewal feature. You will be sent a renewal email 60 days prior to your expiration date advising that your credit card will be charged in 30 days, allowing you to receive your new membership cards in a timely manner. If you don't want your Admirals Club membership to automatically renew, after you renew or purchase your membership online, you can opt-out of the auto renewal program."

So, it seems like only those who joined or renewed in Nov. 2010 or thereafter are in the auto-renew program at this point.

That would not apply to me (Feb. 2010) but I figured I should try to opt-out just in case--so, I tried to opt-out but got the "unable to process your request" message. I assume I'm immune to auto-renewal at this point.