Premiere 5.5 Exports unwanted colour change :s

Hi I've used premiere 5.5 and media encoder to edit a .MTS file created by my Lumix ZS7. I didn't add any effects at all! Infact I tried exporting the source file directly via media encoder.
However, every codec uncompressed to compressed yielded an subtle though unwanted increase/decrease in contrast.

I can confirm that this issue doesn't occur using other applications.

Please help!