Question about frostbite on the combs of my BR roo's

Hi everyone...question about the effects of frostbite on the roo's combs. When I adopted the flock in August (they're all around 2ish) I noticed that the combs of the 2 BR roo's were grayish along the top 1/3 to 1/2 of them. Nothing on the wattles and nothing similar on any of the hens or my mutt rooster. I checked out the pics on here and, yep, it was from frostbite (not surprising considering the conditions that they had been in).

So here's my question...should I be applying vaseline to them now...will it help protect it this winter (we've been having some really cold snaps here). I have really good ventilation in my coop and I see no signs of it on any others. These 2 don't look any worse for wear, and the bottom halves of their combs are nice and red.

Wasn't sure if they were more susceptible to further frostbite damage because of what's already happened.

Any advice would be great! Thanks in advance!

Dawn