I'd like to also ask if the north Koreans were worried about that when they took the ship, but I imagine that's pretty much unknowable
The USS Pueblo capture was a blip on the radar. The United States was deeply involved in Vietnam with two major battles surrounding the time the USS Pueblo was captured. In Korea, a hit squad was being hunted from 17 January until 29 January, so the South Koreans and the US Forces-Korea were busy hunting down North Korean assassins. In short, the Pueblo got taken at the worst time for the US and the best time for the North Koreans.
In fact, if anyone was calling to restart the war, it was General Bonesteel, commander of US Forces - Korea:
Bonesteel's idea was even harsher. Already fully emeshed in the aftermath of the Blue House raid, the general reacted with uncharacteristic emotion at this latest North Korean affront: "It was the most inexcusable and infuriating thing," he said. His patience exhausted, Bonesteel argued for a blunt nuclear ultimatum against Kim Il-sung: release the Pueblo or else.
It was the strongest measure ever suggested by Bonesteel and quite possibly the strongest course of action ever recommended by any U.S. theater commander during the nuclear age. If nothing else, it offers an indication of how much pressure rode on Bonesteel's shoulders in January of 1968. The insertion of eighty-two American hostages into an already highly charged and dangerous DPRK-UNC confrontation had, at least for a few hours, brought the normally intellectual Bonesteel to the brink of irrationality. pp 67-68
Leavenworth Papers Number 19 - Scenese from an Unfinished War by Major Daniel P. Bolger
The taking of the USS Pueblo was not an isolated incident. It happened in the midst of the DMZ crisis of 1966-1969. The North Koreans were routinely crossing the border to ambush US and ROK patrols, blow up buildings, and reek general mayhem. The ROK was doing the same to the North, much to the chagrin of Bonesteel, who, as UN commander, had to reign them in as best he could. So while we can look at the Pueblo as this really offensive and isolated incident, in reality, it was part of a larger conflict that the DPRK was pushing. That, combined with trouble in Vietnam, caused the Pueblo to be nothing more than a blip on the radar of most American's conscience.
For more information, check out the book I mentioned above, Scenes from an Unfinished War. Another book I frequently mention for discussion of North Korean Political/Military strategy is * North Korea's Military-Diplomatic Campaigns, 1966-2008* by Narushige Michishita. It's a great book to see that, as crazy as we think the North Koreans are, their actions have a very Machiavellian logic to them and they're fairly predictable.