iPhone 4 Rattling Sound?

[Newbiee]

My iPhone 4 randomly went to the black apple screen while I was using it earlier but turned on again just fine.
So I've been trying to figure out if something is wrong with it and if I shake it the phone makes a rattling sound (probably not the smartest idea)
Is that normal? or is something loose?

 

[cnguyen0320]

Something's up. Take it to Apple

 

[Newbiee]

Are most things replaceable and if I needed a new phone would I be able to get the same kind?

 

[cnguyen0320]

They'll replace it for free if you're still under warranty. Otherwise they'll ask for a fee. They won't repair it. They'll take it and give you a new one.