Dust within the front camera? (iPhone 5S)

A few weeks ago I noticed a few small specs of dust within my iPhone's front camera, I ignored it at first but the problem appears to be getting worse with more dust building up. When comparing photo performance with another iPhone 5S the photos seem washed out and grainy and the phone struggles to focus. The phone is approaching a year old and is still under its warranty. I am unsure if I should take the phone to Apple, what should do?