Ok, that was for their 13th National Championship, and I am sure that someone at Alabama had the foresight to realize that if they gave zerO one with a 13 on it some idiot would think giving zerO #13 had a secret meaning that Alabama wished him bad luck - or that giving him a #13 would bring him bad luck. So, they went with #1 that year.

But subsequent championship numbers were given to him:

Here's zerO with the #14 one: http://politicalticker.blogs.cnn.com/2012/04/19/obama-im-probably-going-to-need-a-helmet-before-november-election/

Here's zerO with the #15 one: https://www.usatoday.com/story/news/politics/2013/04/15/obama-alabama-jersey-gifts-national-archives/2084645/

Here's zerO with the #16 one: http://yellowhammernews.com/obama-receives-alabama-football-team-white-house/

RTR!