My 3 year old grandson mimics

[Beingablessing]

I have posted a concern on my grandson for being aggressive while playing with other children, but a near perfect child when isolated from other kids.  My daughter had a playmate his own age over yesterday and was encouraged that he played very well (he's the only 3 year old in all social aspects of their life).  She was thinking the other kids being older may contribute to his behavior.  During their playtime she realized what an extreme mimicker he is.  To the point that he would follow the other little boy around and at one point the other little boy tripped and fell, so ours went down too.  When the other little boy would cough, so would ours.  Our 3 year old watched everything he did, and did it just like him.  There was no negative behavior.  I'm just wondering if this is normal or could it be an issue.  Is he having a hard time finding his own idenity?  Could his negative behavior around the older kids be as a result of his misunderstanding their behavior (which they can be very aggressive themselves)?  Is there something we should do different?  He did just turn 3 in February.

[Beingablessing]

He's talking better every day.  His pronunciation is still not clear, but we love it.  The way he says some things are so cute, but we do have to explain to others sometime.  

[Sally44]

What is his speech like?