I prewash and dry everything! Even jelly rolls as in my front loaders the handwash cycle is so gentle they hardly fray.
I think fabric grain gets distorted as it is rolled out in the factory...must come out slightly damp or the first rolling really stretches the fabric. The distortion can be extreme, which is why we used to cut fabric by pulling a single thread and cutting along that line, which gives you the true grain of fabric.