Comb concern

[Seth140]

Hello All. So I have a coop here in the Northeast , chickens can go outside when they want and inside , only on really cold days will I ever use heat, I feed them 100% organic diet. Give them flax seeds , only good food, no bread, my question is I’m noticing on some of my dark chickens alittle darkness in the combs. They still eating, they always have water , and if really cold I’ll rub with bag balm, I’ve read about a lot of diseases and u all know how that can be, here’s a pic u can see the dark, and they are still laying eggs..should I be concerned

 

[TheFatBlueCat]

I have a couple of chickens with large red combs (one is my rooster, one is a leghorn hen) and they get odd blackish marks at the tips of their combs all year round (it doesn't get cold enough here for any frostbite concerns). I see it for a day or two and then it's gone. I initially thought sunburn, now I just think it's dirt.