Those darn marvers stay really really hot for a long long time after you have been rolling a nice hot bead on it!
Never ever use a rod of glass to scratch your head! Burned hair smells really bad! Never pick any part of a bead that cracked of the mandrel and thats not why those little glasses of water are on your bench! ie (to put you burned finger in so ya don't tell the teacher what you did!) It's really to cool of your tools!