Girls, who have a baby who constantly sticks out their tongue? We're t…

Girls, who have a baby who constantly sticks out their tongue? We're two months old, a girl, since birth she sticks out her tongue. Now it seems to be doing it much less often, but it hasn't stopped. The pediatrician at the clinic suspects hypothyroidism, but besides sticking out the tongue everything is normal. Could this be some kind of self-expression? Has anyone had this experience?