I am not sure if this is a known issue or if I am doing something wrong.

I need to export a section of the timeline and then re-edit the exported section in a NEW project.

I used the Premiere export feature and went with the default settings for the project 1080i (footage was recorded with the FX1).

When I re-import the footage, it appears squashed - it fill the width but not the full height of the frame.

Am I doing something wrong on the export? The exported files prooperties show it as 1440 x 1080 but as I said, it does not fill the complete frame.

Today there is bug in Premiere that prevents you from exporting video with 1.33:1 pixel aspect ratio (i.e. the footage from Sony FX1/Z1.) Adobe is about to release patch that fixes this. In the mean-time you can do the operation you want this way :
1) save a project with just the segment(s) you want.
2) Load the other project.
3) Import the saved project into this new project.
4) Nest the sequences (very cool PPro feature), do that the short segment is just a clip on your new timeline.

Thank you David.