Honestly Janet, if that happened to my Jess, I would take her to the AG store, or if that's not possible for you, at least call AG... (Isn't it odd to find some sort of glue in a doll's hair? At least ask them what it could be. As much as we collect these dolls, they are still playthings.)
My Jess was in A+ condition, but I personally selected her after looking at five or six rows of different Jess dolls. They all have slightly differing faces and hair quality, so I wanted to be sure that I picked the right girl. *sigh* I am such a perfectionist when it comes to dolls.
Everyone who sees Jess's "stuff" at my place jokes at how lucky she is... (Her stuff not only comes from Jess's world, but the worlds of Felicity, Molly, AGOT, etc.) Why not? Don't regular folks collect antiques in their homes and wear vintage gowns?