You should probably take him to the doctor to make sure he does not have some sort of infection or virus. They may need to do blood work on him. Also ask for a thryoid test to be done since your thyroid is basically your internal thermometer. Sorry I couldnt be of more help.
My husband did this too a few weeks ago. He woke up in the middle of the night so cold that his teeth were actually chattering in his head and he was shaking with chills. It was hot in the room, close to 80 degrees, but it took wrapping him in 3 comforters and a hot towel before he even began to stop shaking. I wanted to take him to the ER because it's definately not normal but he wouldn't go. He seems fine since then but I have no idea what happened. If it happens to your hubby again I would write everything down and keep a journal if he won't go to the doctor. Better safe than sorry.
It is probably nothing. I have done that at times. If he stays like this, I would ask a physician however, also, take his temp to see if he is running a low grade fever. Did you have any windows in the room open and if so, was it cold out, that is what happens to me, I will be warm when I go to bed, so, I open a window, then, I wake up really cold and have to close it, it then takes a while for me to warm up.