I suspect the camera bumped the ISO rating up to 200 or better where the higher the ISO on a digital camera, the grainier the picture. The way to keep that under control and not wash out the color is to add more light so the camera does not substitute flash and ISO to compensate for a lack of light.
PS: I do like the depth of field you got. I have not gotten use to digital camera's lack of depth control, but I guess that is the price paid for a low cost camera and lens that gives near instant feedback on the little LCD after snapping the picture