I want you to play with you ISO a little. In this image, you shot at a shutter speed that really isn't called for. So, you could slow down to say 1/500 sec. (allowing more light to hit the sensor) and lower your ISO to reduce the "noise" or grain in the background of the image. The lower your ISO - the crisper the image. But low ISOs don't gather as much light. That's why you would slow the shutter to compensate. Good shot though, I like it. Did you throw him a mouse?