Almost the exact same thing happened to me several years ago. There is a park at the end of the street, not far away. The very end house had been rented out, and the owner had met me just before I transitioned and evidently had a big mouth, cos these four kids were playing and as I got out of my car and walked toward my house from the street, this one boy goes, "that's a guy!"
But....
The other three wouldn't believe him, they were like, no way, that's a lady! Love it.