I would say it's normal for dirt to accumulate in that area, especially if you don't have a rear mud guard fitted, but the oily-ness is not normal, especially given the low miles on your machine. It appears the front seal on the bevel box is not sealing, which has been reported here on several occasions, requiring a replacement seal. I did mine with the bevel box removed, but I believe others have done it in situ. Curious what lubricant you are running in the bevel box. Early cars, as yours appears to be, can benefit from a change to a heavy weight gear oil to reduce sound and leakage. Several of us here use Red Line 80W-250 with good results.
FWIW, my 2012 machine came filled with a black paste like lubricant in the BB, which I replaced after removing and thoroughly cleaning the BB internally.
