This problem is more common with softer woods such as maple, rosewood, cocobolo, or boxwood.
It occurs when the instrument is stored incorrectly. The humidity rises while playing. Then the instrument dries out again. During this time, the wood shrinks, but the way the instrument is stored determines if it will keep its shape. We recommend that you always keep it vertical. In this way, the water can drain off and the body retains its shape.