I've noticed that after a long period of sitting, or standing still, when I take a large stride forward (only a large stride will do it) - at the widest point in the stride, there is a slight (painless) tingling sensation in the front of my right shin, just below the knee. It doesn't happen with the left. It feels as if the skin is being slightly stretched.
After I've been walking for a couple of steps - the sensation goes away - even if I make another large stride.
I'm guessing this must be some sort of back issue as pretty much every time you feel something weird in your leg it's a back issue. Have I fvcked up a disc or something?
That would suck as I've been extremely careful in my training and form - and my back is pain-free - but I guess you could easily have messed up your back without knowing it...