Hi R.. My grandson (who live with me, my husband and his mom) is 20 months now. He has been doing exactly as your son is from right about the same time as yours started. He is STILL doing it so as far as outgrowing it, that hasn't happened. It hasn't bothered me too much because he takes it back out when he's taking his next bite. His pediatrician said not to worry it was not a big deal and that his toddler does the same thing. I'm sorry I can't give you any good advice on how to make it stop (maybe some of the other moms can), but just wanted to reassure you that it's happening in our family too and the pedi said when he was ready, he would stop so that's what we're doing - just waiting for him to not want to do it anymore.