newbroom:
All kidding aside, if, indeed, it has changed color on its own, then you might want to consult a physician just to make certain that it is not a harbinger of disease. I do not mean to cause alarm; however, there is no sense in taking any chances.
I hope that you find this suggestion to be helpful.
If nothing else be thankful that it's just white and red/brown.
I've been trying to grow a stache for about a month now and it's multi-colored... If this keeps up and I become a pirate they'll eventually call me "Rainbow beard".