Well clearly he wasn't happy with something - at least he didnt waste several hours of your time, a fiver of your petrol, etc etc. He turned up and left as soon as he realised it wasn't what he wanted. Perhaps he was after a certain spec, forgot to ask if it had it so felt foolish for not asking? Perhaps he was after something with a few less swirl marks? Perhaps he had regrets about whether the 2.0T was the right engine?
Who knows.
What I bet, though, is he didnt thumb threw Autotrader and decide to waste your time for the lulz.