The sides of the tufts of your carpet appear a lighter, more silvery shade than when they are viewed end-on. As the pile settles lighter and darker patches will develop where the pile angle varies according to the amount of use each area of the carpet is receiving. It is quite common for the pile to settle in a different direction to the normal pile lay if the foot traffic bends it this way and this can make the contrast very noticeable (sometimes making the patches appear to have distinct borders). This is why the shading is sometimes referred to as ‘pile reversal’, but this term is only used to describe what has happened and does not indicate that the carpet is faulty. The angle of the pile has no effect on the durability of the carpet and we are confident it will continue to give you many years of satisfactory service.