There's a actually pretty huge segment of Christianity that does not believe in Original Sin. The idea being that children are born innocent, in no need of salvation until they become old enough to become morally accountable. Sin isn't inherited, it's just inevitable because human beings are imperfect. So Jesus did not "inherit" sin from Mary, nor did he ever commit sin during his life on Earth. So, when the events of that passage took place, he was the only one without sin.
[Tangent] Seriously, I never got this whole Mary-worship thing. I've been a Christian for about 1/3 of my life now, and that idea makes even less sense to me now than when I was still agnostic. How is Mary-worship not idolatry? [/tangent]