We are all being investigated by the Feds 24/7 — that's what dragnet surveillance is: indiscriminate investigation at scale to be used retroactively.
"Don't do anything bad and nothing will happen" is frankly asinine to me, personally. That same logic could extend to stop-and-frisk or random door-to-door visits to check for citizenship.
Never trust news about the DPRK from South Korean spy agencies. It's only a matter of months before it's proven to be nonsense. They're the ones always saying crap like "North Koreans push their trains by hand" or "Kim Jong Un claims to have invented the hamburger." Only the most brainwashed westerners buy it, but it's enough to keep the DPRK hate at a simmer.