Unwilling to start

Hello! My bike (GS 1200 twin cam year 2012, 56 000 kms) has behaved badly two times this summer: When starting the cold engine it tries to start normally but eventually does not start running. Maybe I have lifted my thumb too early from the starter button, it is possible. Anyway, after that it has been very difficult to start the engine, several long attempts and then just one cylinder starts, and only after few seconds the other cylinder joins the choir. No other symptoms, the bike has been extremely reliable. Any ideas?

Seems like an air leak somewhere, throw a PM at Steptoe sure he can give you a better idea.

Fuel pump
Coil(s)
Air leak