Have you ever sprained your ankle? Even if you didn’t need crutches, you (naturally) hobbled around, putting more weight on your non-injured side. And perhaps to your amazement, you began to get pain in the muscles or joints of the non-injured side.
All because one side of your body took a little bit more of your weight (which you move around all the time, I might add) for a prolonged period of time - perhaps as short as a matter of days.
What if you (knowingly or not) always pressed harder with your dominant arm? Or allowed your knees to drift in ever so slightly on each rep of leg press?
It’s worth taking a critical look at your form (and rejiggering your weight loads if necessary).