Gray patches on beaks

[Lkase]

I have two Buff Orpingtons that have grayish patches at the very top of their beaks. I'm just wondering if this is normal? This is the best picture I could get. They are almost 3 months old.

 

[loohoo]

2 of our Buffs have this as well. I dont know exactly what it is but I've thought it was similar to a bruise. They peck through the hardware cloth of their run and I just always assumed it "bruised", but I'll be interested to hear what others have to say.
Either way, its happened off and on to our girls over the past months with no consequence so I assume its nothing to worry about.