lack of usage of one side

My son seems to be active with one side of his body (right) more than the other. He will play with toys with his right (will do it with the left if I ignigiate it) and kicks more with his right etc. he will grab both his feet with both hands etc so he does move them just way more with the right. Im going to ask our ped but we don't have an apt for 2 more weeks. Anyone have experience with this? He will be 4 months old in a couple days.