I just went to a Crystal Healing Workshop yesterday- and I asked about the Smoky Quartz. I told him Glaxony's ex-boyfreind's experience with it, and he was not surprised.
The Crystal Healer teacher said it was because the boyfreind could not let go of some negativity within him, that the crystal became hot in his hands, because it was drawing out the negativity-- but the boyfriend was not ready in his life to let that negativity go.
My guess is that maybe , because of that-- energy got backed up within the crystal , which was why it got hot. Heat is involved with energy. ?