I thought I had this figured out. Today when I hit my "Zero All" button with all axes zero'd and homed, it actually moves the machine to X1 Y1. Here's the code. Hitting the individual zero buttons works as it should.
inst = mc.mcGetInstance()
rc = mc.mcAxisSetPos(inst, 0, 0)
rc = mc.mcAxisSetPos(inst, 1, 0)
rc = mc.mcAxisSetPos(inst, 2, 0)