Whether you got a great deal "statistically" or not, I'd say you got a good deal on a new car. I did basically the same thing when I bought my 350. Some guy "bought it for his wife" and traded it in for a BMW and the Z had less than 400 miles on it.
I figured it was kind of like, "Hey honey, look at this beautiful drill I bought you for Christmas", which she promptly took back for diamonds.
Congrats on the new ride.