screw in headphone jack?

No idea but it doesn't sound good !

I'd take it into the Apple store and have a Genius take a look at it - if there are no obvious signs of external damage and the moisture sensor isn't tripped then they may just swap it for another one if its still covered by Applecare/Warranty.

If its out of warranty and its a problem for you, you may have to pay the set Out of Warranty fee to get it swapped out.

To my knowledge there is no screw inside the headphone jack port...

Unless it's hidden under the white water damage indicator tab...

To date I have not heard of that indicator coming lose and allowing what's underneath it to come out or show... like a screw...

ShadyMac wrote:
To my knowledge there is no screw inside the headphone jack port...

That's correct, however there are 4 phillips #00 screws that secure the headphone jack. Knowing where they are, I'd have to say it's almost impossible for one to get lose and protrude through the jack. More than likely what's happened here is a screw from a pocket somehow got lodged in there & an attempt to put headphones in has pretty much force fit it. I've seen pearls lodged in these ports(yes, pearls) pellets, etc. To the OP, go to an Apple store, they "may" be able to get it out, if not, you're gonna have to find a third party repair shop & have the headphone jack replaced. The jacks cost + or - $50.00 US, plus labor. I do not recommend you do this on your own.