D600 Serial Number Query

I am a proud owner of a D600 no dust or oil problems either but one thing that has been worrying me is the Tag on the bottom of the camera where is located the serial number.

On my D700 it's a printed number, on the D600 it was a blanked out area where the serial number was written with a ball point pen, I accidentally rubbed this area and the number came off.

Is this what the serial number is like on other D600 cameras.