I think you may be correct, in the sense that they may have been trying to guage our reaction, to see if how quickly and effectively any anti-missile systems we have in place can react, and (as others have pointed out) to thumb KJI's nose at us.
Given that our stuff can pinpoint the location of any such launch, we knew it wasn't The Big Missile even before it left the pad. We probably know more about the performance of that rocket than the North Koreans do....
Boiled frog?
They may be trying to desensitize world opinion by making a number of provocative baby steps, ending with the launch of a long range missile. The thinking may be, that with NK missiles going off all time, there's no threshold crossed, no point at which American public opinion turns decisively in favor of action against NK.
Remember 9-12-01? Who would have thought that the American public would become tired of the WOT this quickly and this easily?