Hey I'm in your class!!
joking, it sounds like you have z+ limit set up as a limit switch and not a home switch. Mine is set up as a home so it doesn't trip the fault during toolchange, etc. You have to be carefull this way though, as their will be no more limit switch at the top, the steppers really don't have enough torque to do damage anyway though. You could use the lower z+ switch as a homing switch and the upper z+ switch as limit, but you will lose 1/4" of travel.
If you try to make everything idiot proof, someone will just breed a better idiot!