You did well and, with the original box, you did very well.
From the label (TEB serial number prefix and Spec. Ord. number) it appears the pistol was manufactured in very, very late 1989 and probably shipped in around January or February 1990. You might note that the numbers under the barcode consist of the Serial Number followed by the Product Code followed by the Spec. Ord. number. So, covering just the "Serial Number" didn't do it.
The early model 3913s not only had the flattened slide release mentioned by 18DAI, they also had a flattened safety lever. Well, at least flatter than those made after around 1994 or so. It does not look like it was carried at all (lack of dings and especially the nice condition of the grip), or at least hardly at all. Just out of curiousity, did you find the little tool kit, instruction sheet and brown S&W paper in the box?
I've had 4 3913s and still own 3. They're great. All 4 would do the following, if I did my job. Of course, I don't post photos from those shooting sessions where I didn't do my job.
