I think I've pinpointed it. When the game loads your name colour (I think it's the first time you open the menu and any time after that when you level up) it's this colour for a moment. After that moment it loads in correctly. Sometimes it doesn't load in at all, and that's when you get this.
[Edit]: It doesn't look like it reloads it when you level up. Could just be the first time it loads it in then, and it doesn't re-load it when you switch to a character with another name.