With the final bars of opening number Drive My Car still ringing in their ears, Paul McCartney raised his index finger to his lips, licked it and then lifted it in the direction of the 1,000 assembled for his first British show since 2004. Of all the performer-to-audience icebreakers, this 'You're hot' to the rogue's gallery of monied middle-aged faces assembled in London's Electric Ballroom - most of whom looked as if they'd rustled a free ticket - seemed almost entirely inappropriate.
This isn't to say there wasn't enthusiasm in the air. This was, after all, a rare opportunity to see a Beatle playing the Beatles in a venue chosen specifically for its intimacy, but a sense of sheer curiosity seemed to be keeping the temperature in check.
There was also a distinct air of sobriety. Anyone under the age of 25 - and there were few - appeared to be accompanied by well-heeled parents. The concert was supposed to have been secret, but in these days of PR spin, this had become a marketing tool in itself. London's The Evening Standard had even offered tickets to 10 callers to a premium-rate telephone hotline, and the show was publicised, rather desperately, on the radio and internet.
The large crowd that had gathered outside, ostensibly to grab a quota of first-come-first served admissions, seemed to have swelled by the time the show was over, suggesting that most were there to gawp at the celebrities on the guest list leaving rather than to see the great man perform. (That this list included former 007 Pierce Brosnan, former Arsenal FC David Dein, actress Emma Thompson and Pink Floyd's David Gilmour - no sign of Oasis' Gallagher brothers, although Kate Moss arrived belatedly - might have proved a disappointment and underlined the fact that, for all the publicists' efforts, this wasn't to be the hippest night on the London calendar).
And although he has always seemed to insist that, with him, it's all about McCartney the music, on this evening it was going to be a great deal about McCartney the man. The reasons for this were simple: a lot of troubled water has passed under the McCartney bridge during the past three years, not least the divorce from second wife Heather Mills, a split to which the word acrimonious doesn't begin to do justice. It's not that anyone in this audience surely could have believed the stories from her camp of his drunken, cruel and misogynist behaviour. But they've left a few nagging questions about a character we'd taken for granted as reliably nice for so long.
And here was the man himself, conveniently up close. Perhaps a momentary steely gaze or a stolen shrug might betray an insight into a personality different to one that we'd assumed for all those years.