[Turing_Machine]

There are many possibilities. My money is based on the fact that iOS 11 just came out. "Hmm... I see that there's a new iOS....Better update my personal phone even though I'm not using it at the moment...Wow! This phone is acting weird! Better take it to the security people at work."

I don't know that's what happened, but it's certainly plausible. If it is, it speaks well for Kelly's powers of observation (noticing that the phone was behaving in an unusual way) and ability to choose a proper course of action (taking it to the security professionals at the White House, rather than, as someone else noted, Geek Squad or whatever minimum wage clerk was manning the counter at the Verizon store).