Why did Moving In take so long?

[Venn]

In my new town (because I did a reset), Penelope moved out when the town reached 9 villagers. However, I know that it usually take around 2 days for a new villager to move in. I've noticed that this didn't happen and I feared that someone would still move, although I knew that at least 9 villagers had to be in town for 1 to move. Four days after Penelope officially moved, Celia came to me saying that she wishes to move and I allow her to, but there was never a ninth villager. A minute later, I saw a piece of land being taken for a new home, Chester.

I was so confused why it took so long, and how a villager not even moved in somehow triggered the game to allow one to move out. Can someone explain this, or was this just a game glitch or something?

 

[Mary]

The ninth villager usually takes longer.

 

[Venn]

This was after the the 9th Villager, Chester is the 10th.

 

[Gummysaur]

10th villagers don't randomly move in, you can only invite them from Campsite, StreetPass, or from someone else.

 

[Venn]

I guess I'm not being clear here, let me rephrase.
Penelope = Starter Villager, who moved away once a total of 9 villagers lived in the town on 2/11
Celia = A Villager who moved in after the starter villagers and moving on 2/21 and announced today 2/15
Chester = A villager who has his plot down on 2/15 and moving in on 2/16

So when my town first hit 9 villagers, it spent a few days with no new villagers. On 2/10 it was announced that Penelope is moving away on 2/11. 2/12, 2/13, 2/14 has no new plot for a house. 2/15 Celia announces she is moving when Chester has a plot but not even moved in. So for four days, I've had 8 villagers, but when Chester took land for his plot, it triggered the game for Celia to move, although Chester hasn't officially moved in yet.

I played many games before this and a town before this, so I know it usually takes 2 days for a new villager.
I was so confused why it took so long, and how a villager not even moved in somehow triggered the game to allow one to move out. Can someone explain this, or was this just a game glitch or something?

 

[Gizmodo]

That is odd as surely if Chester had not arrived, you would have been down to 7 villagers if you let Celia go :s? which im sure the game wouldn't have allowed, but still its odd

 

[Superpenguin]

Sometimes the game just takes a while to give you some villagers.