I would advise you to see a dentist so they can assess your crown for you. It would be very difficult, if not impossible, to accurately measure the thickness of the crown once it has been cemented.
It’s possible that the dent you can see is part of the design of the crown (to mimic tooth morphology/shape) and this area may also have a different texture/feel/colour due to the adjustment your dentist provided.
However for peace of mind, I would recommend you see a dentist as there is also a possibility that the crown was over trimmed.
Hope this helps!