There are pre-facelift 02 plates and even facelift 51 plates knocking about. It's not really when they were made, more like when they were registered. Some cars can sit in compounds for years before they are registered, yours was one of them.

Prime example of this is the escorts. Production of them was stopped in 98 'S' reg when the Focus was released, but they were still being registered and sold as new up to X or maybe even Y reg.

So you have just got a pre-faccelift that was hanging around a long time before it was registered and sold.