I have a similar issue with my S seats, but more in the middle of the seat and not quite as pronounced (yet). It's most noticeable after just getting out of the seat. The cushion does seem to regain its shape (leaving less of an indent) after a while of getting out of the seat I don't wear a wallet in my back pocket, but if you do, it might be contributing to it.
Also, I have the exact same wrinkling on my side bolsters as you have. In fact, the car (with 15 miles) was delivered to me like that. I questioned the dealer. A few people in management at the dealership reviewed and concluded it was normal. My response was: "Normal? For 15 miles? What's it going to look like after 15,000 miles?" However, I decided to accept delivery anyway. Also, for whatever it's worth, a pamphlet on the leather was included with my car from Jaguar, which did mention something about it being normal for the natural leather to develop some lines/wrinkling.