increased body temperature during meditation Is it common during samatha for the body temperature to rise enough to cause  some isolated forms of sweating? Specifically around the head, like where a hat would set and sometimes across the upper chest and shoulders? 

It doesn't happen every time but at least several times a week. The room temperature is well regulated and in no way warm. I also noticed that there may be a correlation to some insomnia on the same nights that the sweating occurs during the meditation.
There's all kinds of wackiness that can occur during meditation.  Some of it is mental, some of it is somatic, and still other phenomenon are a blend of the two.  None of these things are any reason for concern and it's best not to pay them much mind.  Some of these experiences will come and go while others are will appear quite regularly almost becoming like your own personal brand of meditation.  To be honest, elevated body temperature is actually pretty tame compared some of the other stuff that can happen.  Just wait until your skull twists into a spiral, your hands inflate to the size of beach balls, and you suddenly find yourself sitting at the lunch table on the 117 day of fifth grade!