This happened to me last Thursday. I knew I was supposed to get Leif that day, and Gullivarrr on Friday. But I paid for Leif's RV on Wednesday, so I ended up with Leif on Harv's because his RV opened and none of the rotating visiting NPCs that Thursday. In hindsight I should've just waited a day for paying off Leif's RV, but I thought it'd just replace him with another NPC.I see, thanks. This is really weird though. I've got no visitors.
Maybe I was supposed to get Leif today, but then today is the opening day on Harv's. That would be the logical explanation.