@medquest That's an interesting question. Herpes can be spread by intimate contact - kissing, sex, etc - before symptoms appear. Direct spreading through casual or incidental contact (ie sipping from the same cup) is less risky UNLESS there are open sores weeping liquid.
Here is what Mayo Clinic has to say about the virus:
https://www.mayoclinic.org/diseases-conditions/cold-sore/symptoms-causes/syc-20371017.
Have you let the person know that you got a cold sore soon after they sipped from your cup? If they are susceptible, any symptoms would typically appear in 2-10 days.

If you are like me, or other members of my family, who have frequent and sometimes severe outbreaks of cold sores, we never share cups, forks, chapstick, lip gloss, etc. And I never try makeup samples in the store.

People used to think my Mom was "quirky" back in the 50's and 60's because she never let us share - we even had 8 separate, identified bathroom cups lined up for the family. Many years later I figured out she was practicing infection control!