My plot is gone...?

[AkashiXI]

Is there any policy with buying a plot and not purchasing a house on it for x amount of days? That'd be my first assumption, as seeing how it could cause players to buy a plot to reserve (or sell) for another player.

Edit: I wrote that before refreshing my page. Honestly I think it's a smart idea - if you have enough gil to buy a plot, you should have enough to purchase the house. I can totally understand SE not wanting you or others "reserving" their plots for future use, especially since the same practice coincide with RMT.