2 month old pumping left leg?

Sami • 🌻1.31.18💙

We have our two month appointment Thursday... obviously I'm gonna ask our ped, but doesn't anyone know how concerning this is? He pumps his left leg A LOT when he's excited or upset. He can move both at the same time, one at a time, and his legs seem the same length with no noticeable fat roll difference in either leg. Pretty symmetrical.. but I'm driving myself nuts worrying if he's okay or if I'm doing something wrong 😔