I think I know which one you mean. Most likely it's original. I've seen OD-1s that decode to 1989 as well. Note how it's got the long black label with room for a serial sticker on the label. Only the last ones had that. It is surprisingly clean, especially for a pedal sold without a box.
Since MullyFX was considering buying it I didn't want to post the link in case someone gazumped him after seeing the link here. It might not be the same one anyway but I'll let MullyFX decide whether to post it or not.