Honestly, it's completely normal for little kids to experiment with the sounds and actions they can make with their bodies.
At this point, I wouldn't be too concerned. I really wouldn't.
I went through a phase of walking around with my eyes half shut because I thought people would think I was Chinese. My blonde hair couldn't possibly be a giveaway, right?
Looking back, I was just a weird and imaginative little kid. I'm so glad my mom didn't rush me off to a neurologist. My teachers did recommend that I be tested. It turns out I had an incredibly high I.Q. I didn't know what that meant and I was allowed to be a normal, strange, and creative little kid.
I have a grandson now. I think that younger moms tend to worry too much about every little thing meaning there is something "wrong".
Little kids get a free pass to be silly and imaginative.
I'm not downplaying true and valid concerns. I just think that sometimes we are too quick to think the worst.
Best wishes!