I went to my dealership today and the guy that sold me the car told me the demo car he uses doesnt always catch first time but it doesnt do the catch, revs up, fall down, cut out that mine does. I took it in, told the mechanic who started it again & again about 10 times and it started every time (Sod's Law!). They updated the software and said if it happens again or regularly then to bring it in for a day of diagnostics.

He told me to keep a look out for the egine management light coming on because the computer records everything that goes wrong and that light should pop up.

Hope this is of some help