Greg sold Mitch a fishing boat for $8,500, maintaining to Mitch that the boat was in excellent condition. Mitch gave Greg a check for $8,500, which Greg endorsed and gave to Denise in exchange for a debt he owed her. When Mitch took his friends out on the boat, he discovered that the boat leaked, needed to be painted, and required a new motor. Mitch stopped payment on the check, which had not yet been cashed.

Does Greg still have any rights as the holder?