This has only happened today. I haven't altered any settings.
I have the OP posts as a certain colour and they show up within a thread as that colour. Now, out the blue, there is the odd poster who is another colour. For no reason. It isn't the OP, it isn't me (another colour), it's just a random poster on most threads I've clicked on and it's not the same poster each time. Does that make sense?
(I thought it might be those whose profiles are public but some are and some aren't so it's not that.)
What's special about these posters? 
(It's just a bit strange as it's only happened today...)