It hasn't actually happened in about a month, so I'm not sure exactly what's going on. I think it's my hip or belt that is bumping the switch. I should try to replicate it when I practice tonight and see what happens.
I did try adjusting my strap last week and raising it up a little bit because the ZX was hanging a little low. That could have contributed to it happening in the past. If I can eliminate it altogether without voiding my warranty, though, that would be best for me. I am the kind of klutz that would do fine for a few months, think that everything was better, and then bump it while up on stage in the middle of a performance.
The problem I think will be finding something that will suitably cover the switch without interfering with the rubber foot, so it has to be shallower than the foot. My friend has a CNC mill so he might be able to make something for me in a pinch.