Strange issue with my Rhode Island Red hen...

Hello,

I have only two hens right now, a Rhode Island Red and a Barred Plymouth Rock. They're both Standard-sized hens.

I have a really strange issue with the Rhode Island Red. Today, I was examining her, and, when I pushed back the feathers on her back (the ones that are right above the very start of her tail), I noticed a tiny bit of really hard, upwardly-angled skin. I didn't exactly want to touch it, in case it was a sign of illness, but when I gently touched it with a piece of straw, Pippi (the RIR hen) didn't seem to be in any pain, or anything...So, I put her back into the coop, and I checked the Barred Rock, Lucy. The two hens couldn't have looked more different! There was no sign of anything on Lucy's back!

So, I'm wondering if Pippi (the slightly older hen) might be dealing with a medical malformation of some kind, or if the odd bit of raised skin is normal for her breed.

Thank you in advance for any information that you may have, with regards to this matter, because I am completely confused...LOL!

Bye for Now,
Rustic Light