GUI button texture different color when script is on Instantiated object

I'm having a very strange problem. I have buttons with little white arrows on them as the button contents. These are called in OnGUI within a script attached to a Prefab. If I have the object with this script attached in the scene at the start, they look fine and white. If the object is Instantiated, however, the textures are gray, and the buttons looks a little bit different.

I have no idea what could possibly be causing this. If anyone has any ideas, please let me know!