I used to get it often when I was having a "psychic growth spurt."

I think its simply an increase of energy in parts of the mind that are usually devoid of it, and that the end result of it is the development of various metaphysical skills and a clean cut connection between the conscious and subconscious mind.

I found that before the tingling occurred I had a lot of pressure building up and lots of headaches which died down once the growth spurt had begun. After the growth spurt the heat/chills and crawling sensations and pins-and-needles tingling sensations all died down.

I could not link my own development to the Kundalini as I never experienced the feeling of that energy stirring and rising up my spine, but that is only my experience so the reason for what you're feeling could be completely different.

I do know that a lot of people get this and I think that it is most likely connected to a growing of spiritual awareness of some kind.