The idea is that graphene will transfer electricity faster than silicone. And since its carbon and it has a very strong bond it will heal itself, may be a slow process. But, never the less the chip could heal.
This is a bit of a random thought. The chip could develop a kind of microchip cancer. Any imperfection in the chip would cause microchip tumors to grow and change response times in the CPUs clock and cause bad/ random data.