Yes, this is the case. When I got my logic board replaced in my previous machine apple said the operating system would not know the serial number. There is nothing you can do about this. I had to de-authorize all my machines and reauthorize them in Itunes. You will have to look on the machine for serial number now. I would write it down so you do not have take the battery out each time you call apple. I called apple about this multiple times asking if there was a way to put the serial number back.
They told no, thats how it is.
Message was edited by: mac wise