Apistogramma viejita with a red "shoulder"?

[JosVermeulen]

So I've had this male A. viejita for a while known, but it seems to be developing red on it's shoulder. I took pics of it as you can see below (with and without flash, don't mind the dirty glass). I've never seen this in other A. viejita, but I know that this one is F1 from near Puerto Gaitan, so I wonder what it could be?

 

[Tom C]

I have dirty glass in my A. viejita tanks too

These are F1 from the type locality too.
As you see, the big male in the middle has developed some of the same colors as yours, and so has a couple of his brothers. So this seems to be a natural color variation within this species... You wouldn't dare to selective breed them to in the end produce a A. viejita "Red shoulder"!