There haven't been many happy moments over the past five years for Finnish smartphone player Nokia (NOK -0.97%). Although Apple and Google have changed the game in the smartphone space since 2007, Nokia has been slowly eyeing a return to relevance with its flagship Lumia line of smartphones. In fact, the company gave investors a bit of a shot in the arm last quarter, when it posted stronger-than-expected Lumia sales in its most recent quarterly report. However, this encouraging number doesn't have everyone impressed. In this video, tech and telecom analyst Andrew Tonner warns investors that booming Lumia sales could contain a hidden bomb.