iOS - GUI.Label not displaying correct size

I have a splash image at 640x960 size, and I want it to stay on screen once the game is loaded, as a backdrop to the main menu. I am using the following code:

GUI.Label( new Rect( 0, 0, Screen.width, Screen.height ), splash );

But for some reason the image displays slightly smaller than the screen. When loading on the device, the loading splash itself (same image) is perfect, but appears to shrink slightly once replaced by the OnGUI label. I tried changing to 512x768 with the same result. I also tried 512x512 which made the image stretch properly to the right hand side, but it wasn’t scaled - it was still displaying square.

I’ve also tried changing the line with no success to:

GUI.Label( new Rect( 0, 0, 640, 960 ), splash );

The import settings I’m using are: Aniso level 0, Filter mode Bilinear, Wrap mode clamp, Texture type GUI, Max size 1024, Format Truecolor.

D’oh! Sorted it myself. It was as simple as changing the settings in the GUISkin I’m using for padding and margins. And I’m using GUI.Box now instead, although I don’t know if that makes a difference.