I feel for you man, that sucks. I'm definately careful where I park my car, but in a crowded lot, what can you do.
Could of been a kid or some old lady, and completely accidental on their part, so you never know.
I wouldn't bother going through insurance though as that will probably cost you more in the long run. Your probably better off taking the hit and fixing it yourself.
But hmmm.... a 13 inch ding on a new car. Bummer bro.