I didn't plot resett when Aurora moved in (after inviting her from the campsite). She put her house right in back of Town Hall.
I resett/deleted my old town before I got to the stage when I could sell it. I didn't realize at the time that the town tree had to be at a certain stage in order to sell your town.
Seems like Aurora was keeping tabs on Isabelle and you.
Oh..ouch. I wouldn't have know that too about the town tree/selling town. That's a bummer, sorry.