Knowing the kind of person who does all the things you mentioned, it was probably a striker-fired pistol too (Gun everywhere, round-always-chambered people typically dont want anything with a hammer that can snag on their clothes when they do their cowboy quickdraw). Build quality being equal, a striker pistol should be about as safe as a hammer pistol, most of the time...unless you take it into a crazy strong electromagnetic field, in which case you'd better hope it has some kind of drop-safety to keep the striker from being magnetically yoinked forward into the chamber.

If it didn't go off as soon as she walked in, I assume she shifted position in a way that lined up the gun with the magnet to make that exact kind of malfunction possible

Bonus from the article about America's most popular striker pistol randomly shooting it's owners in the legs:

Additionally, this same news outlet reported that the Army’s approval of the P320 led many police departments to adopt this weapon. However, they were unaware that the model they would be receiving was the version that had failed Army testing.