When did you last wash your hair? Unless your hair is extremely dirty, I would still feed the milk to the baby, but probably wouldn't freeze it for later consumption. You wouldn't be particularly concerned if the baby got one of your hairs in his/her mouth, I imagine.
How old is your baby? Are there any health issues?
I probably would still use it. If the milk is just being expressed now, the antibodies etc are still alive, and so would destroy any bacteria from the hair. I would be reasonably careful with the milk re: refridgerating etc, but then you always have to be.