Exporting to Quicktime: clips edges of frame??

I've used FCP quite a lot, but this is stumping me:

I'm editing footage which is 1920 x 1080 HDTV 1080i (16:9), pixel aspect ratio is square, field dominance is upper (odd), compressor is pro res 422.

Using FCP 7.

In the canvas the framing is perfect.

I export uncompressed to Quicktime movie selecting "use current settings".

When I play back the.mov file in quicktime or preview, the edges of the clip are cropped very slightly. It's only noticable because I am filming a TV front and so the edges of the TV screen are meant to be slightly inside the .mov frame, but at the moment they are being cropped so you can't see them, if that makes sense.

How can I correct this?? Or is it just a standard anomoly that isnt normally noticable because normally the framing doesn't have to be 100% accurate (i reckon it's only cropping about 6 or so pixels from each side).

Thanks!!