Not sure if I’m being paranoid... White on tail?

[Linkisnotzelda]

My axolotl Oaki has always had a white spot on his tail, but now it seems to be getting bigger and his tail is kind of translucent. His water parameters are normal, except for a slight increase in temperature (which I regulate by opening windows a crack at night and having an aquarium fan on all day. He also is very active during the night, but he’s always been like this. What do you guys think? Should I be worried, or is he just losing pigments? I know axies can lose some color when they get older, but he’s not even a year yet. Any help would be appreciated!