you just got your bike? i would say if u have "metal rubbing against metal sound" it might be the pads have alrd worn to its limit. pls get it changed. also, removing the pads from the bike to inspect, is fairly easy. you can do it yourself with the right tools fairly easily and fast. do checkout youtube videos regarding removing the caliper. Here is a youtube video on how you can get it done yourself. or if u dun have the experience, i will recommend you to bring it down to your trusted mechanic.