I had a quick check at the back of my recorder and retail box and both the serial #'s and manufacturer's dates match. My Serial # starts with a M0151... and has a manufactured date of April 2005.
At least your recorder is newer than what's on the box, however it does indicate that that the box the recorder came in was not the original box for that recorder.
The best thing to do is have a quick look around the DVD recorder to see if there are any scratches or other signs of use. If you have not attached any leads or cables to it yet, you could check the connections on the back for faint / light scratches that would indicate that they have been used at some prior stage. Finally, if you have not used any of the cables or removed the cables from their plastic wrapping, have a close at these to see if any of the plastic wrappings were opened at a previous stage or if the cable ties shows signs of being previously removed. It is quite dificult to reuse a cable-tie a second time without it looking like it has been used before.