Hi Goom! Thanks for posting here.
I believe this is a bug (or "feature", I'm not sure) in Unity. This happens when you set the resolution to "iPad Wide (1024x768)", and the window can't display 1024x768 pixels. What this happens, Unity will start compressing the viewport vertically, which results in gaps appearing.
If your display is unable to display the window in that resolution, simply set the game window to "iPad Wide (4:3)" instead of the explicit resolution. The issue doesn't occur when running in this mode.