C902 fastport(battery charging port)

hi guys when ever i remove my usb cable hand free or battery charger i can hear a strange sound "creeking" sound very low. is their a defect in my phone or is this sound normal for c902 or is it the usb cable hand free or battery charger that are causing this sound. if something happens to the fastport in future will my warrenty cover it.
should i complain everything else is working.

is this normal or should i worry

its normal my cousin has c902 it hapens