Weinsteins thought they had a dud on their hands, so they didn't want to go wide with it and spend the cash on prints. The fact that it continues to expand is good for its prospects of a wide release. The same thing happened with My Big Fat Greek Wedding - they didn't know if they're be an audience, so they expanded it slowly. It went on to wide release and great success. Fanboys per-screen average has been ok but not spectacular, so it's hard to tell at this point what'll end up happening. I think the lack of advertising hasn't helped it.