S.A.
it's probably just teething but even if it's not - a runny nose alone isn't significant enough to warrant going to the doctor. If it's a cold, then it's a virus and there's nothing the doctor can do anyway (antibiotics are only for bacterial infections). However, keep an eye on the color of the mucus - it's normal to be yellow or green after he gets up in the morning or after a nap but if it's consistently running yellow or green that could signal something more than teething.