2.5TDi 48K oilpump failure=new engine :-(..

That pretty much sums it up. I have owned my 2.5tdi VW T4 transporter december 2002 from new. I purchased it to use as a personal vehice(surf van) so has never carried any weight. I have always been very pleased with it appart from the other warrenty issues and poor service I received from my dealer. Oil pump failed in december and have just got my van back after it took the garage 1month to get things right. Good job for me that it happened during the warrenty period.

My question is simple, why would I get oilpump failure on such a lightly used vehicle?