Give him some time. He's been in a program for a year. For a year he was safe and protected and learning that it's scary out there for an alcoholic and it's easy to falter. I know when I got out of treatment, which was only for six weeks, I was scared to death. I didn't want to leave the treatment facility because I knew I was safe there.
So, it could be that, or it could be any number of things. Maybe just step back and let him come to you if that's what he decides he wants. Otherwise, just go on with your life and wish him the best.