It sounds like the officer is cutting you a break. You aren't being criminally charged. Warnings don't accumulate conviction points on your license but the police department might keep a record for themselves that they already pulled you over and gave you a warning previously.
In addition to the fine, your auto insurance will eventually find out about this citation and the conviction points it will add. Your insurance might non-renew you or they might significantly increase your premiums for the next few years. If you are non-renewed, other carriers will find out about the citation when they run your record and it will almost certainly be a factor in them determining how much to charge you themselves.