Crosshair and Cursor centering to different positions

Hello,

My cursor has been centered and locked using Screen.lockCursor, and my GUI crosshair has been centered using this code:

 //crosshair position and dimensions
 crosshairRect = new Rect((Screen.width - crosshairTexture.width)/2, (Screen.height - crosshairTexture.height)/2, crosshairTexture.width, crosshairTexture.height);

When I unlock the cursor to show its position (ie. in the pause menu), the cursor is slightly north of center. This problem is noticeable ingame as you must hover over objects to highlight them.

Does anybody know why this might be happening?

Note: This happens both in the editor and in the build.