Man, don't listen to what anybody says about your hair or anything else... I'm 44 and my hair is literally halfway down my back. There are still people who think that when you reach a "certain age" you should start to conform to what society
expects of you and become a drone like everyone else... This has more to do with
them than you.
I even know some people who act surprised when I tell them about whatever band or musical project I happen to be engaged in at the time. They say things like "You're still playing music?? I would have thought you'd have given up on that by now..."
Given up??
Like music is just a means to an end, and if you're not touring the world or playing in the Tonight Show band by the time you're 30, then you should put all that "foolishness" behind you and sell all your gear, buy a rocking chair and take up a more "sensible" passtime - like scrimshaw or stamp collecting - while you wait to die.
These people don't understand what life is about. They gave up on their own passion years ago and are resentful of those who won't abandon theirs...
However, I digress...
Life is too short to worry about what
other people think of your hair, your clothes, the kind of car you drive (whether you wear sunglasses on stage

) or any other meaningless criteria. If they don't like it, it's their problem, not yours.
[Edit] BTW, no offense intended to anyone who enjoys scrimshaw or stamp collecting.... Or wearing sunglasses on stage.