It's possible that Stanford has been a team that has been overlooked coming into this season by their opponents so far. With their obvious success this year, next year they will have a target on their back and their record next season may come back down to reality in the PAC-10 (maybe 3, maybe 4, or 5 losses next season). Anything can happen.
Anyone that follows college football know that this happens a lot. For example, Kansas a few years ago. They had a great season, but couldn't repeat their success with Todd Reecing coming back as their starting qb. I think teams that year were more prepared for them.