Here is a photo, there is of course the normal place, then at the rear of the frame under the RH grip are two more, one right behind the grip screw hole and one just under the hammer pin. Notice that the one closer to the barrel is much smaller. My theory at this time is that the laser operator was testing the laser, but if others are also marked in those places then there must be another reason for it.

Thanks to anyone who can answer this mystery.