This was my exact thought. We used to live in Yaletown (downtown Vancouver) and literally every single person we knew there would spend all their free time doing outdoorsy things (one of the reasons I was glad to move away from there lol). Grouse Mountain is a popular nearby place for hiking but it's not uncommon for people to head up towards Whistler, too, as there are many buses to take you there from many points in the city. All of that to say, there could be a potentially enormous search area if something bad has happened (God forbid). Not to mention, extremely spotty cell service...
On a separate note... I don't read too much into Natsumi's body language. Honestly, I gesticulate wildly even when describing paint drying... some of us just have happy hands and so it's hard to interpret the tone of the conversation based on that...
Hope that today will be the day Natsumi comes home.