My 2 week old sons leg shakes for few seconds and then stops?

Sounds normal: In early infancy a baby has little control of their limbs. They can control head movement side to side & sucking & head lift, but there are many random reflexive movements early on in their limbs. By 4 months most can grasp & let go with hands but leg control will come later. This is not a seizure and not a sign of other bad stuff.Enjoy your baby & get ready for more confusing events to come.