Like any of the band's 80,000 screaming fans that night, his then girlfriend naturally took a snap to capture the excitement.
Unlike other gig-goers however, it doesn't show the young couple smiling out from the crowd, or even Bono and his bandmates doing their thing on stage.
Instead, it freeze-framed Darragh in the grip of an internet fixation – recording the gig on one gadget and tweeting non-stop on another.
Reformed Twitter addict Darragh (34) who lives in Dublin 8, admits he barely remembers going to such events.
"I've gone to things where I was videoing or tweeting or whatever, and I don't remember that I've been there, because I wasn't really there," says Darragh, a community manager with WorldIrish.com.
"I was so eager to communicate to other people that I wasn't really experiencing it. That photo was a huge wake-up call for me.
"I have this love/hate relationship with the internet," he explains. "I need to use it for work, but I became a little bit too dependent on it.
"It really, really consumed me. I couldn't put down the internet. I suppose it was more of an addiction to the connection – the FOMO [Fear Of Missing Out]."
This month Internet Use Disorder (IUD) – or internet addiction – has been accepted as a "condition for further study" by the Diagnostic and Statistical Manual of Mental Disorders (DSM-V), an internationally recognised classification system of mental disorders published by the American Psychiatric Association.
With studies showing that one-in-four of us now spend more time surfing the web than sleeping, however, some addiction experts here argue that it doesn't go far enough.
"There is almost a chuckle when people talk about internet addiction," says Dr Garrett McGovern, Medical Addiction Specialist at Priority Medical Clinic in Dundrum.
"It doesn't have an official status – but I think it's a matter of time.
"There is no doubt that it has many of the same features of other behavioural addictions such as gambling, in terms of time spent on it and other things.
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