Probably have you previously had a runny nose? By chance did you heal from it? Naturally you recovered! You won't treat a runny nose itself, however your body generally develops immunity to a specific cold virus within a few days. That is called cured by your very own immune response!

Adults have currently had a great deal of the runny nose viruses. Grownups have developed resistance to the colds they have actually had. So there are not lots of cold infections remaining for parents to catch. That is why adults only succumb to a few colds annually and kids may get 10-12 colds each year.
https://amara.org/en/profiles/profile/P2HSK3IOhqbeY48aUQZdwkSFAocl0STSlzrK9kJJxvU/