I've not had the problem in the past.... however i always charge my battery's in an Ammo Case (you can pick these up in some ex army supply stores)
Drill a small hole on one edge of the case so you can slip the charging cable in and close the lid with battery's inside, be sure the hole drilled is a tight fit to the cable without cutting into the charging cable!!!
Put the charging box on the floor preferably a concrete floor, if you have one, away from anything combustible, like gas lines, (ovens) curtains etc...
Although it won't stop a fire breaking out it can seriously reduce how quickly it burns out, as the smoke will fill the case and suffocate the flames after a short period of time, This method of charging will not stop a fire if the transformer catch fire but that is less common then battery's going poof, especially lipos if not charged correctly, there bleeding lethal!
3 things to do ... check your house insurance policy's to make sure there up to date, and they cover fire ( you won't believe how many policy's are out there that don't cover fire!)
Make sure all fire alarms work!, and a nice strong word of complaint the manufacture providing that you can prove you did not do something silly like short the wires or anything to void the guarantee, some type of compensation, full refund of the product or at least a written appoligy should be make to you.
Me.. i would go all out and see what i can get, but im like that anyway.. something for nothing is always nice