I've got dust under my camera lens cover!

So as I said I've got some dust particles under my rear camera lens cover (the little round glass piece that sits on the back of the phone, covering my cam). I think it got there through the microphone next to the camera, but I don't know how to remove it. Really annoying, so far I haven't seen any impact on my photos, maybe they got a little more blurry..

I still have warranty for my phone (iPhone 5S btw), but I've got a tiny hairline crack on my screen, just next to home button, so I don't know if they'll clean this for free of charge in an Apple Store, we all know Apple.. Any suggestions guys?