I've exchanged emails with the seller. I specifically asked him if the crack was in the body, or just in the paint on the surface. He said:
" the crack in the body is about 4 inches long and hasn't got any worse since i've owned the guitar (which is over 2 years), it's a mystery to me why it's there, my theory is it was left somewhere hot, who knows, i think that answers all your questions, feel free to ask any more."