Sometimes the leather or rubber on the grips of lenses and camera bodies tend to turn whitish in color. This is typically from exposure to air, and nothing to worry about. It can happen on new or old equipment, and can happen on any brand. Some brands are more prone, such as older Minolta lenses. The white is hardest to clean off from a camera body because of the leather used, and easiest to clean from lens grips.
Here's our #1 tip for cleaning the white up, for aesthetic purposes only.... Take a toothbrush to it! Use a new/never used/clean toothbrush with harder bristles. Use the brush only on the grip area, and gently rub back and forth, in the direction of the grooves. The white should come right off. Now, if there's also dirt and grime on the grip, you may need to also swab a Q-tip with some cleaner such as Windex and wipe it with that as well.