I'm 30 days on Monday also! I don't think it is a guarantee that you will relapse if you don't go to AA. But I do think that you need to be involved in some type of recovery group. We all need a place to listen and to vent without any risks. AA is not the only place that provides that but it sure is a great one!
We talked at our meeting the other day about picking up a start over chip and that for many it is pride that keeps them sober. They sure aren't coming back to a meeting and telling everyone that they have slipped. So if they wern't going to AA they wouldn't have to tell anyone if they started drinking again.
Just be sure you have a strong network of people to talk too and you have a better chance!!