Difference in size of baby's calf muscles?

[scmama]

I don't really know how to word this, but I'll try and explain. DS is 10.5 months old. He is an active crawling, standing, climbing, and trying to walk baby. One of his favorite things to do, is tap and kick his left foot while standing (he gets a great leg work out). He is doing this so often that his left calf muscle is much bigger and much more noticeable than his right calf. Is this normal? Should I try and stop him from kicking and stamping his left foot? I've tried to get him to kick his right foot, but he just isn't interested. I've just never heard of this before, and as he's my first baby, I just wasn't sure if this was normal. I put him in shorts today and you could really see the difference in size of his leg muscles. My MIL mentioned something about this today and kind of made me feel horrible for not worrying about this before. I feel so silly asking about this, but I just wanted to see if anyone else had experienced this.

Thanks.