You should consider yourself double-y blessed...
1) It was a false alarm and your DD has been protected from any trauma surrounding the incident
2) You have received a warning call that many folks never get--as evidenced from the posts on this thread.
I thank you from the bottom of my heart for sharing all that you learned.
I have been struggling with what I call "parent pressure" to give my DD(7) freedoms and responsibilities that I don't feel it is safe to do given this day and age. (And I also live in a lovely, middle to upper class suburband niefhborhood.) But you just never know.
As a result of your thread, I am sticking to my guns. If I don't feel comfortable with a situation, it is not happening. My new philosophy is go ahead, and call me the overprotective dork of the neighborhood. When I can safely send my DD off to college knowing that her childhood was not marred in this way, it will all be worth it.
ps--You cannot feel guilty about this. Just reading your thread brought tears to my eyes--I can only imagine how many tears you have shed over this incident. You make decisions based on the information you have. Now that you have more information, you will make different decisions. Its as simple as that.
Now. I gotta go do carpool...and hug my DD and DS. Everybody else should do the same!