If it is indeed a crack, contact Look to see if there is a lifetime warranty on the frame (assuming you are the original owner and can prove it. You did keep your sales slip, right?). If so they will replace the frame at no cost. If the warranty has a specified time period, like 3 years, they may have a crash replacement policy that provides a replacement frame at lower cost.

Otherwise, new frame time or contact Craig Calfee for a repair estimate.