[ChrisZang]

You actually got lucky.
Almost the same happened to me last year when I was at Porscheplatz parking at the American LeMans race in Laguna Seca.
I opened the rear trunk to throw in my jacket (it was a nice and sunny day). Unfortunately I also threw in the keys...
I closed the trunk and the car auto-locked itself after 30 seconds.
In my case after AAA had opened the doors I was still out of luck as the car had sensed that it was "broken into" and disabled ALL buttons. So I could NOT open the rear trunk and get to the keys. (And the alarm was blaring to everyone's annoyance). Did I mention that I also locked my wallet and my cell phone in the trunk?
Long story short: I finally found a very nice Porsche owner (Gerry from Santa Barbara) to drive me from Laguna to my home in San Carlos (where I had my spare key) and back to Laguna.