Android : Cardboard Unity - Black Borders Missing on Stereo image

Hi I'm using the Cardboard Sdk for unity with Unity 4.6.3 - as recommended in the sdk docs.

Everything works fine and builds and runs to my android phones except for one issue: there are no black borders around the stereo image (the edge part of the screen where the grey line and the settings cog icon are) Bits of the stereo image get smeared around the unrefreshed edges.

This happens on multiple phones so it's not the phone..