I am just getting into jazz guitar. Ordered my first archtop. A washburn j600. It was used and the seller alleged it to be in excellent condition. When I opened it up I checked it over and found two cracks along the neck starting just at the nut. One follows where the fretboard meets the wood of the neck and the other goes into the neck and down about an inch and a half. The intonation is good, but I never know how much to be concerned of hairline cracks. What do you guys think? Lesson learned about buying used guitars online, nothing to worry about, or something to try to get a return on? Thanks in advance.