Am I teaching him to be passive?

[jelnel]

My son is 2 1/2 years old and unlike other kids I see he never has had a problem sharing even as a 1 year old . I wonder if this is good for him he is very passive in a group setting he accepts things as they are and when in music class when the teacher hands out instruments instead of going for the one he wants he will try but back off if kids get in his way then look at me like what am I suppose to do?I know its a learning process but the only time I have seen him get aggressive with other kids is with a child he has known from birth and at there house.Then he just kinda pushed him back when he was pushed by the child but I have seen him take a toy from this child.
Is he too passive Im afraid he is missing out on things because he doesn't go for what he wants He will gladly just move on to another toy if someone takes one from him