When the screen is centered on an object, depending on the device, the screen is not centered well.
How to reproduce the bug:
Set the application size to "640x960" (iPhone4 size)
Always center screen at 0,0 of an object which move (like a bouncing ball)
Set application iOS option to "fit inside and resize frame"
Run the application on an iPhone5 or iPad =>
> on iPhone5 you'll have a mis-alignment on Y (the difference between height of iPhone5 and height of iPhone4)
> on iPad you'll have a mis-alignment on X (the difference between width*ratio of iPad and width of iPhone4)
The workaround is to use the object "Window control" to get the window frame size and to compare with the frame size (which is still the original value). However, it's a strange behaviour I think.