Don't worry. It's normal.
The fix for this issue is powering the elecromagents 24 X 7 thereby limiting the free movement of lens.
But why we need to exert extra pressure on the battery for something not worthy?
The sound you are hearing is totally normal - it's actually because the device lenses are flexible to give you better image quality.
However, excessive shaking or throwing of the phone will make it worse.
You can always get your device checked at the nearest Samsung Service Center if you have any doubt.
If you are hearing rattling sound when shaking the device, then it is normal because it is due to the mechanism of auto focus in the camera of the phone. So a tip would be: don't shake the device violently and don't worry about the sound - it's totally normal.