By any chance does she have any developmental issues such as poor muscle tone? My son was gross motor delayed to to hypotonia (poor muscle tone) and also had sensory issues. He used to lick everything from the walls, to the floor, to the couch. He also gagged on things that were too textured, like oatmeal, and on things to sweet like Tylenol cherry flavor liquid. Eventually, he did stop licking things but I think he was over 2 by the time he stopped.
It still seems normal, if it worrys you give her something like a rattle and see if she wants to chew,Maybe some teeth are coming through and her Gums are sore, she doesnt know how to express it,does she lick with enjoyment , check back with the Doc if she keeps doing it.