Did you find out whether it was a paint or frame crack. I have a Jamis with exactly the same problem, crack looks exactly the same and carbon seat stay bonded to aluminium tube. I took it to the LBS and they sent it off to be load tested. He said they load it with a force and measure the delfections, if its cracked it should be larger than normal. He said the deflections were fine and that it was just a paint crack. Not sure whether to trust him as i was looking to buy the bike off a friends of bloke at the shop.
