Am I a smuggler?

I just thought about it while reading a newspaper article. On trips to US, I have brought many cameras back for my friends, relatives and myself. For all these cameras (4 of them), I did not pay any duties. One of them was very expensive ( $1300). I have been to US 4 times and I am aware that I can bring one camera for my personal use per trip. So technically, I did not break any rule. Still, I felt the guilt of bending one. Now you people tell me - Was I wrong not to pay any custom duties?