Hi Suzieq,
In my experience, that is not a normal reaction. Those that are close to me fully support my decision and would never hold my past behavior over my head, and those who are acquaintances usually just say "oh okay" and move onto a new topic. Is it possible this person struggles with addiction, themselves? I remember when I was still actively drinking and someone would say they stopped or don't like to anymore, I would mentally make some sort of argument for them drinking in the future... Because if some random person stopped for good, why couldn't I?
At any rate, I hope you get understanding responses in the future
You should give yourself a pat on the back for being able to remind yourself of who you are now and brush that person's comments off. I hope someday soon I am that strong