my macbook pro battery not charging fully 100%

I recently brought my brand new macbook pro 2weeks ago, and realise my battery NOT charging to 100%, it use to stay at 99% and now it stay at 96%, I restarted it, and still the same, I shut it down and charge it over night, that is when it never charged over 96%, the charger light turns green indecate that it is full, also the battery test on the side shows all the lights it show that it is full, but the battery icon shows 96%, this might get worst, what should i do,