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 depending on how the instrument is stored, it is determined whether it keeps its shape. We recommend that you always keep it vertical. In this way, the water can drain off and the body retains its shape.