Did you use some liquid from a bottle to clean your dashboard top? The shine could have been from the silicone or wax content in the liquid which they say will prevent damage(cracking and discolouring) from solar glare and UV rays. I have make it a point not to use them on my dash top and don't have this problem. Just use light soapy water to clean. Theres only dust there, no grease to get rid of. The shine can be reduced or got rid off by using something that won't damage the dash top's plastic surface. Many car yards use this liquid to make the dash shiny just to impress would-be buyers. Looks good when you're not driving in it. When you're driving in it in bright sunshine, you won't be able to see whats on the road in front of you especially if the dash top has the leather look on it. You can also instal the dash protector which has a carpet material on top guaranteed not to shine. It fits with velcro or doublesided tape.