I don't know what it isDont know yet whats up with the brightness, i allready made a very dark specular, could be also something that is hardcoded.
It's possible that the post-processing is causing it in some levels (I haven't looked at other levels).
And to make matters worse it is not visible in the character-preview either.
Although it does look like that white/bright colours are affected the most.
ie : your 'white' mouse is almost a glowing bright spot. The other skin isn't even half as bright although his highlights suffer somewhat.
Maybe there is something in the colours and materials used that makes them glow ?
It may be somewhere in the teamskin-related materials.
// -- edit --
I have the post-processing set to 'extreme', returning to 'default' kind of solves by reducing the glow-effect significantly.