Faded fin on P. Cory

[CanadianWaters]

Does anyone else have panda cories that appear to have a faded dorsal fin (that is the fin on top right?)
I can take pictures later if needed

 

[Sidman24]

I know that cories ( at least emerald ) turn colors like a paler color to blend in to their territory, etc. I'm not sure if this applies to pandas as well. But usually the color always comes back the following morning.

 

[CanadianWaters]

No the fins have been faded permantly and the colour doesn't return.
Honestly I'm not too worried as they have been like this since...maybe when I bought them and they seem healthy and happy.
Thanks though!
That's pretty cool and Cory's do that!