Some feedback and issues on the Viper Mini

I received my Viper Mini today an I really like the shape. The plastic feels a little bit slippery but thanks to the light weight it isnt that big of a deal. Buttons are ok. Better than the ones on my Model O but worse than G403. Cable, Mousefeet, Mousewheel also all feel great and the shell feels very durable. My copy of the Viper Mini has some very annoying and loud sensor/lense rattle though. It even is noticable when I just normaly use the mouse during gameplay and not just when I shake it in my hand. When I put black tape on the sensor and shake the mouse I can see the mouse cursor move around. This doesnt happen on any of my other mice I own... Is this normal for this mouse or did I receive a poor copy? If so can I get it replaced by razer via warrenty?