Since it leads back to the screw on the far left, it's probably a stress crack due to over-tightening the neck screw. The angle/lighting of the picture probably makes it look worse than it is. Finish cracks happen and it sucks finding them on a new-to-you guitar, but most important is how it sounds and plays.
If the seller didn't disclose it in the listing, you may want to ask for a few $$$ back, but it kind of goes with the territory of buying a used guitar. Reverb's condition rating leaves some flexibility for sellers to claim their guitars are in "very good" or "excellent" condition and still allow for things like this because it's fairly common and can happen during shipping (at no fault to the seller).
Still a very nice guitar regardless.