A MAJOR plot hole

Rating: 7/10 (25 May 2012)

So I liked the film and was mildly entertained, although it was slow at places ... but one HUGE thing bothered me throughout ...
How was it that EVERYONE else EXCEPT J didn't remember K being alive? I mean, the time line skewed into a tangent since Boris went back in time and killed K. How come J (Will Smith) still remembered him, or even worked for MiB since it was K that recruited him post death. Makes no sense to me.
There's a scene where he's about to time jump where he asks the radio shack guy how that can be ... but there's never an answer to that question?