It's certainly a possibility, but what purpose would it serve the DPRK? It would knock continental US for six, this is true, but it would do jack about the ROK and the US forces in Japan and Korea and would not do much to stop a US carrier group from steaming into Korean waters and flattening anything it saw. Furthermore, since it would be pretty obvious (since you can bet that satellite is being monitored) who conducted the attack then it would be a carte blanche for the US to wipe the DPRK leadership off the planet.
No matter which way around you look at it, the end result is the fiery destruction of the Kim regime, and I can't see Kim doing that, his situation is dire, yes, but he is still well fed, well protected and in power, and his people are cowed enough not to rise up against him. The only wild card is the military, and that's most likely who all this sabre rattling is aimed at pleasing, once Little Kim has the military on side then his rule is fairly cosy.