Is something wrong with my macbook pro with retina? I got the 13" yesterday and did a test on coconut battery and it says that the maximum charge is 89.1% and the design capacity is 100%.
Please do not worry, you are misinterpreting the results.
Maximum charge is currently (at the time of your snapshot) 89.1 % out of 100 % ,or, in other words it has drained down to 89.1 % while you have been using it.
Design capacity is currently (at the time of your snapshot) 100 %, this is exactly what you should expect if you got your MBP yesterday.
The design capacity will wear down (through use) over time and is an indicator of how well your battery is doing.