Hi yall . Inside of my iphone 5 some rattling sound . u guys' phone has same Cuz in genius bar they said it's normal but it's not most iphone 5s don't sound like this

Hi yall. I had been to genius bar they said it's normal it's ok but when i hear my friends' ones there is no noise like this ... What should i do ? Does your phone have the same rattling noise ? It sounds like just a small thing is moving freely there