I would take the view that getting vaccinated does not constitute "exposure to COVID". Delta's website refers the reader to the Centers for Disease Control definition of exposure, which is at the following link.
Public Health Guidance for Community-Related Exposure | CDC
Since vaccination is not listed here, I think you can affirmatively certify with confidence that you have not been exposed to COVID as the result of being vaccinated.
If I'm wrong, please let me know, as I am scheduled to fly one day after my second COVID shot (I got my first such shot two days ago).