IPhone 3G Crackling Noises?

When I turn on my iPhone 3G (With my headphones on), I hear a little bit of crackling just before the phone enters the main menu. Also, everytime I plug in my Headphones, or any headphones, i can hear a little crackle and a pop sound through the headphones. Apart from that, there is no problem. I dont hear any cracking after the headphones have been connected. Music plays fine, never had any problems, just this. Cud anyone please check this for me? or tell me if this is something to worry about or not... Thanks!