Hi Alix,
If it is a peculiar sensation, similiar to nerves jumping in your legs (you can sometimes see the veins moving/beating), nothing painful but odd like mini electric current feel, then according to our GP it is very common (especially in older people - *owzat ducks to avoid low flying missiles*) nothing to worry about [gave it a name but cannot remember] and said to my hubby, not to be concerned, it will come and go.
If this is not what you are referring to, then ignore this message - it wasn't me that sent it !! Lol