Why does my iPhone 4S home button sound like its cracking?

Lately my home button sounds crunchy like when I press it once it sounds as if I pressed it twice and crunchy as if it was a double click sound also it is very loud as if it was rusty. How can i fix this?

When i had my iphone 3gs, way back when, i eventually came up with the same problem, i took it to apple to get it fixed, when i went to go and pick it up, they said that there was dirt gathered up under the button.id see if apple could fix it for you, or just take it apart yourself and get it outta there, but that can become a whole project.