Thanks for the replies. And thanks for the link, Mike. I especially liked jmlutz's post: "new owners can have hell sometimes." AMEN to that! And it's a comfort to know that even "old hands" can get idiot scratches, too.
I've got a photo. Not sure if it can be of any help. But Mike is correct; I jammed the slide while trying to line things up to get the slide stop reinserted.
Mike has already asked me to verify that I was not holding the grip safety at the time. I was not.
I've heard that Nighthawk has superb technical support. I plan to be on the phone with them in the morning.
Again, thanks to all!