A.J.
I would just say they out grow it. I have 4 kids(3girls and 1boy) and all 4(including my son) do this. It could be more for babies of mother's with long hair I guess, but not sure. Just something comforting to them. My 4yr old has done this since she was born, as the rest of them, and sucks her thumb still. She also has an attachment to her snoopy blanket she's had since birth.
But it's just something they'll out grow or maybe not. My 6yr old hasn't played with hair for a long time. All of them started out playing with mine then moved on to their own. I'm 27 and still twirl my hair when I'm bored. I would honestly say it's a good indicator of how their mood is. If she's doing it when she's tired then when you see her doing it you'll know she's needing a nap or bedtime.
To me I don't think it's a big deal. But I'd say if you're more comfortable with her having a blanket, just give that to her when she starts getting ready to sleep or whatever she does with the hair. You could keep your hair pulled up so it's not there when she's eating. But if it's an attachment to the hair, she could easily start playing with her's instead.
