Unless they speculated on a possible cause, who can know?
I remember when I went through the revolver armorer class and the instructor emphasized some attention and care when working near the rebound slide spring frame stud, since replacing the frame stud for damage caused by improperly applying force can cost upwards of $125 ... and that's if a new stud can be installed and the frame doesn't require replacement.
A broken frame stud isn't something that seems to happen with any frequency. Not unless someone removes the slide plate and starts to tinker around inside without knowledge & experience.
I own five J-frames, four chambered in .38 and one in .357 Magnum. They get a fair amount of use for training/practice/quals, etc. Three have aluminum alloy frames, one has a scandium aluminum frame and one is steel. The alloy guns get the most use nowadays, both on the range and for carry.
I have another scandium aluminum J on the way, too.