Black spots on comb (pics included)

[Gardenlady2]

I've seen small black spots on my roosters combs before and just assumed they were small patches of frostbite, but the past several days/nights haven't been much below freezing, and yesterday I noticed a black line on my Delaware rooster's comb. What is it?

 

[Alaskan]

Odd, I would think he scratched it on something.

 

[Wyandottes7]

It looks like he got pecked by another bird, or scratched it on something (wire, etc).