"Speckles"

This is not a problem, per se, but something I've always been curious about. Both my sister and I have "speckles" in our hair. We have dark hair and they show up as white dots sprinkled along the lenth of the hair shaft. You can't see them unless you're really looking for them. While we've had many hairstylists exclaim over them (including bringing others around to look at them), we've never had anyone say, "oh, yeah, I've seen those before..."Does anyone else have these, or know what they are?