D.M.
My son did this and I mentioned it at his 3 month visit. They said maybe it was a stroke in utero, so they wanted to do an MRI. So be prepared to hear something along those lines. As far as I have heard from talking with other moms when we were going through this, most heard the same thing. Our son did not have a stroke however. He had another condition (caused by my thyroid being wacky) that caused his muscles on his left side to be tight. As he got older his left hand would stay in a fist and get even tighter the more he concentrated on doing something. He was never really weird about his legs, his was mostly his hand and arm. If you want to talk more feel free to message me on here. I will explain more if you would like, just don't want to write a novel on here :) Eitherway, if he has already had his 3 month visit, then I would call and make an appt and not wait until his next well visit (as other moms have said) Props to you for noticing youself. My doc said normally things like that are not caught until they are older because parents just think their kids are right/left handed...but truth is at that age, they should not prefer either and you are right on to question this.