It's probably genuine. The production of the digital pedals like the PS-2, DC-3 and DD-3 were the last to move. I have yet to see a MIT DC-3 but Boss says they made it up until 1993. If that's the case there may have been Japanese production 6 years after they started moving the factory.
on a slightly different topic, i just bought a HM-3. the decoder said it was made in March of 93 but according to the description, they werent made till April. is this common??