Unlike most other stocks, Facebook (NASDAQ: FB) shares didn’t exactly get off to a flying start in 2013. The social network’s stock had declined more than 6% year-to-date entering the day. On Thursday, Facebook shares rose 3.2%, closing at their highest level since March 13. A new smartphone app seemed to be the catalyst. Available on Android’s operating system, the app greets users every time they use their handsets. It will be available for download on April 12. The new app is another victory for Facebook in the company’s efforts to broaden its mobile presence. The social network did a solid job of breaking into that market last year, as 57% more people used their mobile app than they did in 2011. Some analysts have been skeptical about where Facebook will be able to continue growing its revenues . Mobile could be the last frontier. Any progress in that area is likely to give Facebook shares a nice boost. If that’s the case, at $27 a share the stock will need plenty more advances in its mobile business to ever get back to its $38 IPO price.