Question: Leucistic Axolotl gaining black spots, Sick?

Three months ago I bought these two little cuties from a local pet store in Lansing Michigan. The Black one is a Wild/Leopard morph, while the white one is a Leucisitc.

About three weeks into owning them I noticed the white one began gaining little black dots on his face and head, my Leucisitic before him had those as well, which was usually just dirt or algae stuck to his face so I didn't worry about it.

One day I tried wiping it off, as I had done with my previous Axie, but the spots were on his skin. Over the course of the last two months he has gained more and more black as he gets older and bigger.

I was wondering if there could be something wrong with him? or if he is maybe a leopard leucistic mix and the patterns are showing up more as he grows?

His behavior is normal, he eats well, and is very active.

The first picture should be him the day I got him, the second a few weeks after, and the last is him now. (the black one is just my other Axie!)

He is fine. He is just heavily marked, and very pretty!

Some Leucistic Axolotls produce melanophores which is the dark brown or black skin pigment you see speckling your Axolotls head.

Axolotls - Genetics and Colour

Okay!! Thanks Guys! I just wanted to make sure. My other Leucistic stayed completely white with beautiful pink gills, so I didn't have any experience with color changes!

This is Wooper, my first Axie who unfortunately passed away
(He loved climbing in his plants! )

Some leucistics get dark coloring on their gills. One of the names for this is "blue gill", and there is a genetic component to it, but I haven't seen anything to indicate whether or not it is controlled by a single gene. One of our leucies has pink gills, one started developing blue gills when she was about 1 year old, and two others (and some of their siblings) were developing the coloration when they were about 4 months old.