ok ... how many months ago was your last ML purchase (that she knows about ... secret stuff doesn't go into the equation) ... take that number of weeks ... this is the gestational period of the average ML (I assume you're talking about a long gun - rifle, smooth rifle, musket or shotgun. etc. - handguns have a shorter period).
tell her that someone (imply it was her mistake) turned out the light in the shop, and, well, boys will be boys, and there you go... this one was two weeks preemie, so it will need special attention.
when the swelling goes down and some of your hearing returns, let me know how this works ... i'm about to make the same mistake myself...