Yes, and this is worth knowing before the first wear. Shungite contains a large amount of carbon, and both polished and unpolished pieces may leave dark marks on skin or fabric. The effect is most noticeable while the stone is new or when it is rubbed against light-colored clothes. This is a normal property of the material, not a quality issue or a fault in the pendant.
To limit the marks, start with a simple test: wear the pendant over a dark or old garment for the first few times, or hold the stone against a white cloth and rub gently to see how much it transfers. You can also wipe the pendant with a soft, dry cloth before wearing it — this removes loose carbon dust from the surface, which is often the source of the immediate marks. From time to time, lightly wipe the stone during the day if you notice dark transfer on skin.
If you plan to wear the pendant with delicate or very light materials, for example a white silk blouse or a light wool sweater, be a little more cautious. The transfer is not permanent in most cases, but it can be visible and requires care. This caution is not a reason to avoid the pendant; it simply means choosing when and how to wear it.
Keep in mind that this dark residue does not indicate that the stone is crumbling or degrading — it comes from the carbon-rich surface and is a normal trade-off for owning a raw-mineral accessory.