Is it offensive when i call a child little person?

Okay so me and my sister were walking down the street one day. And we kind of sort of walked into like a small child. And for some reason i went, " oh my god a little person." And my sistet laughed. But its kinda cause i hate kids too. Is it offensive to call a child a little person? Cause now i feel really bad that "a little person" sort of burst out of my mouth