Body indentations may be visible when your new mattress is first used.
This is common and is simply a result of the normal settlement of the new materials used in the manufacturing of your mattress.
This will settle after a few weeks of usage.
You will need to rotate or turn & rotate you mattress to allow the fillings to settle correctly. Not turning your mattress will also invalidate your mattress as it is part of the product care.
More information about rotating your mattress can be found here.