Weird movement in my legs- what caused it?

I woke up this morning and I was just lying on my side in bed, there was this surge down my body towards my legs and they twitched- it was the weirdest feeling. It's never happened to me before, I mean I get twitches in my body all the time, but this one was quite violent and there was this surging feeling from my chest downwards. What caused it? Should I be concerned?