It might have just been an upgrade, but it could indicate that it is a Genesis 3000 model actually.  I am not quite so knowledgeable on that era of grill.  But, the info I posted earlier was direct from the Weber C/S web site.  also, as Larry M. stated, some stores, like ACE back in the day would do those upgrades in house to get a customer to commit to buying a certain grill.  Kinda like telling a truck buyer customer they will put in a bed liner on a truck if they buy it.