Dean, what is the VIN # of your Volt (the last 8 characters such as CU101999). It may not have had the replacement EVSE done (there was a customer-satisfaction "recall" done on the original charger). The 16ga wire was a dumb move on that one, obviously and the replacement one is better.
Did you call the fire dept after you put the fire out to make sure all was good in the wall?
My neighbor mentioned that she had to call the fire department after she had a fire start and run up a wall in her house because a socket shorted out while using a lamp in it. So, all sorts of things can happen. She didn't put the fire out but they did after arriving within 4 minutes of the call and saved her house.