My dealer claims these rear engine seals are a "crapshoot" with no real rhyme or reason as to why some fail and others do not (excepting of course if you have been driving around with a clogged flametrap, which could indeed explain it)

My base 5-spd has 210k miles (mostly long haul, but not necessarily highway miles) and has shown no signs of leakage, not even an oil seep, anywhere and I still have the original clutch. I will change the rear seal when I finally need to do the clutch. If your car has had a lot of city miles, you may want to consider changing out the clutch while it is opened up. Certainly worth having a close look at it. Good luck with it. It is a shame such a cheap little part takes so many hours to get at.