Was I lied to? Axolotl face injury inquiry.

Hello.
I purchased two lovely axolotls the other day from a local pet/exotic store. Both seem to be in very good shape gill wise and weight however my melanistic axolotl, Bone, has what I was told was a healed over mouth injury. I got them for a discount because of this.
However I want to make sure I wasn't lied to. The pet store claims that the axolotl came to them from the breeder with the injury and that it was healed. I don't know much about what cuts look like on them. So I guess three questions:
1. Is it healed or is it still healing?
2. If it isn't healed how can I help It? The tank is at 66°F 18.88°C. Tank is cycled with ammonia .00 nitrite .00 and nitrate between 5-10ppm. pH about 7.3.
3. If it is healed will the skin ever be black like the rest of his body?
Help a newbie axolotl dad out?

I included some photos of Bone, one from the store and two from the first day I had them in the tank.

Axolotls should, for the most part, heal fully. Give it some time, and keep the temperature optimal. It looks as though it is healing, just watch out for white fluffy bits, which is fungus.
I think it should get the colour back, any injuries mine have had normal colouring after.