It's hard to predict when war will break out, but Sweden wants to make sure that it's populace is always prepared for the worst. "Worry" isn't really the right term.
They are very much aware of the possibility. Norway is in NATO because it shares a border with Russia and was concerned about Russian expansionism after the end of World War II. A few years earlier Russia’s invasion of Georgia, despite my dire warnings, also took the world by surprise. Over the last two weeks, every household in Sweden received a booklet of instructions on how to prepare for war.
Sweden’s prime minister, Stefan Löfven, told a national defence conference this week that he “cannot rule out” Russia trying to influence the country’s next elections, which are due in 2018. Being a Swede myself and an avid amateur historian of WW2, the role of Sweden during the war is a fascinating topic for me.