Crack on Carbon Frame?
According to Cannondales website they offer limited lifetime warranties on their frames. They also have a passage that states"The specific warranty covering your Cannondale bicycle is governed by the law of the state or country in which it was purchased, and applies only to bicycles purchased from Authorized Cannondale Retailers". That said my first stop would be the dealer that you bought it from. I would stop riding it until they check it out. You don't want a warranty denial due to the fact you rode it damaged. If you get an unsatisfactory response I would seek a second opinion from a shop that specializes in carbon frame repair. I believe most shops don't see enough frames to form a valid opinion. Or they fear litigation (rightfully so) and make a judgment for safety sake.  You may save a few coins if you disassemble the bottom bracket so they can get a look inside the shell. 
  I had a Cervelo R3 with a similar looking flaw. After having it checked by a shop (Hot Tubes) that does custom builds and frame repairs. They determined it was stress cracks in the paint. That was several years ago and it has not gotten worse.