My screen gets some kind of hotspot

Hey everyone for some strange reason my Mac gets what looks to be maybe a hot spot in the lower right hand corner every now and again. I notice it usually most of the time happens when I am playing a game on the Mac for a short period of time....Lately it has been happening more and more even when I do not play a game on the Mac. I will be taking it to the  store tomorrow but I just wanted to see if anyone else has had any similar problems and could shed some light on this. Also what do you think  will do about this problem?

Here are some pictures

Looks like you have a cluster of pixels in the lower right corner of the display that are beginning to die. If the machine is still under warranty, Apple should replace the display at no charge.

Regards.

Hey thanks for the reply....yea I went to the apple store today and they replaced the screen for me free of charge under warranty but they did not say whether or not they knew what the problem was.