I’m not accusing you of doing anything wrong. Im just telling you what I’ve heard many times.
I’m from the south. We have weird ways of pronouncing things too. Sometimes we don’t notice them, it is what it is.
I have 1st cousins from Harlem and Bronx. I’ve went to school with transplants from NYC (Queens, Long Island, Brooklyn, etc. A lisp involves the s sound, that isn’t a lisp. I’m not saying it’s most of NYC, but I’ve heard it enough that it just might be a thing for some people up there. It’s nothing to get defensive about.