A part fell off when I replaced the dock connector...

I recently followed the ifixit instructions on how to replace the dock connector for the iPhone 3G. Everything went perfectly until I switched the phone on. There seemed to be an issue with the signal - I was only getting 2 bars max. I also heard rattling when I gave the phone a shake. So... I then went through the replacement process again and a metal part fell out from what I think to have been underneath the logic board. I have linked to a picture of the part below.

Can anyone tell me where this part has come from and if it could be signal related or what to double check in relation to the signal.

I appreciate any time anyone gives to this.

Thanks.

Picture