New Bosch Classixx 6 doorseal keeps having to be replaced?

Bosch Classixx 6 1200. The machine was bought in March 2010. The door seal continues to rub away at the bottom (seal gets thinner and thinner untill it finally rips) and has been replaced 3 times in the last 9 months. We notice it by small rubber particles being deposited on the washed clothes. We have an extended warranty but I am worried we will need to get the door seal replaced every 3 months for the next 4 years! Is this a known issue? Should I push for a replacement/refund? The technicians have examined the machine and cannot see anything wrong (i.e. misaligned drum or something). They have also discounted user error and things being caught in the seal.