Should I worry about a chipped carbon mountain bike frame? The other day while I was racing my Specialized Stumpjumper I noticed a chip on the frame. It's on the rear support bar right behind the seat post between the rear tire.

My teammate who is a mechanic said its just outer damage, they tapped along the frame without hearing a change in pitch. Others agreed. I brought it into the bike shop the next day and they said that I shouldn't ride the bike and were willing to sell me a new frame. Are they just trying to get money out of me or is it really cracked?
The problem is liability.  Any shop is likely to tell replace as they don't want the liability of it breaking and you getting hurt.  Plus they want to sell you new frame.   

I would go with your team mate the mechanic.   

See if it grows. Even if it does fracture and you fall I bet it will not be your first fall nor fatal.