Recently I noticed two stains on the interior headliner of my XK8 convertible top. The two stains are a few inches long by a quarter inch wide and are above each of the front seats headrest. I was perplexed as to what could be causing the stain until one day when I was putting the top down, I saw that the headliner where the stains are located, comes in to contact with the snaps that hold the tonneau cover in place on the backside of each seat as the top is retracted. This also happens when the top is put up..... A few months ago I had treated the female snaps on the tonneau cover with WD-40 and it must have transferred to the male snap base on the backside of each seat and then to the headliner. Lesson learned....