Probably have you previously been down with a cold virus? Perhaps did you heal from it? Obviously you recovered! You can't treat a runny nose directly, yet your immune system typically establishes immunity to a specific cold virus within several days. We call that healed by your own immune system!

Adults have in the past had a great deal of the rhinitis infections. Adults have developed resistance to the ones they have suffered from. So there are not so many cold infections existing for adults to catch. That is why adults just get infected with a few runny noses per year and kids usually get 10-12 runny noses per year.
http://rowanpyrj421.image-perth.org/hpv-natural-cure-treatment-1