Thanks for your question.
Brief, closed-mouth kissing like you described is low risk, but it is possible for HSV (herpes) to be passed even with brief contact.
You’re correct that when a person is exposed to HSV we would expect to see symptoms develop by 21 days. If you have not seen any lesions appear by 21 days, you can assume you did not come in contact with HSV from that specific encounter.
HSV is usually not dangerous, and it is rare to have any complications with HSV-1 or 2. Encephalitis from HSV is very rare. There can be some danger to new born babies if the mother has open lesions on their genitals while giving birth. There is anti-viral medication that pregnant people can use to prevent lesions during childbirth. For people living with HIV, we rarely see complications with HSV. If you are living with HIV and have questions about HSV please feel free to submit another question for more information.
Hope this helps.