Thank you for the picture. It is slightly hard to tell and I would definitely go to the doctor who performed the procedure to have him/her take a look at it. Darkness after a repair such as yours can be due to bruising, or lack of blood flow to the area. Both can happen after surgery...
You may be surprised to read this, but I see less scarring on the nose than anywhere else on the body. That is because the skin there has many oil glands and a rich blood supply.
So as long as you go with someone who is experienced and careful, you should heal with little or no scar.
Basal cell carcinomas are very slow growing malignancies but if left untreated they can cause bleeding, ulceration and invasion. In some cases they can rarely metastasize. Never leave a basal cell carcinoma untreated as they become a much bigger problem if you don't treat them early...