scrapping noise

Hi there, I bought a used Mazda 3 2010 a few weeks ago (new brake pads, checked by another mechanic) and the car has no noise when driving for the first 15-30 minutes. After that you start hearing this noise at low speeds (similar to when your brake pads are gone) even when you don't push the...

Okay so this started happening a few days ago, when I start driving there seems to be a scrapping noise coming from my tire/brake area. When I apply my brakes it goes away. Sometimes it goes away and sometimes it doesn't but more times it does. And I'm not rue if that's a sign of my brakes...