I've found that some chicks are bigger "babies" than others. That is, they are looking to you to be the momma hen and acting like babies. have you ever watched a mother hen and her chicks? The chicks shelter under wings and breast. Any sign of danger and that's where they head; it's their security blanket. Some chicks are bolder and spend more time up on TOP of the mother hen, others spend more time sheltered under some part of her body. Different personalities.
When hand-raised chicks want to nestle under your hand, or hair, or -when they're a bit older- tuck their head under your elbow.... I think its essentially the same thing. We've found that hand-reared chicks who get a lot of handling really do imprint on you as "mama hen" at first, and then later you change, in their eyes, to "rooster". Some chicks are naturally bolder and others are bigger babies. I have one EE hen who, to this day, snuggles her head under my elbow when I pick her up. She used to do ti all the time as a chick, she was a real "baby".
I agree that perhaps you should not encourage this behavior, though, for the safety of your eyes and earrings (had a chick eat one right out of my daughter's ear once!) Why not try cupping your hand over it, or some other sheltering gesture, to satisfy that need in it?