I recently got a refurb iPhone 6S the other day. I had a launch 6S phone and had become accustomed to the faint vibration that it provides with the new motor. This refurb seems different. It's a bit more harsh and almost has a slight hollow springy sound to it. It's most noticeable when I'm making a phone call and get a text with the phone up to my head. It's not too annoying or anything but definitely seems a bit different. Did they change the motor at all since launch?