I've only seen them on the world map -- and only on 50x50 maps.
LATE EDIT: I should add that unchecking Optimize Tile Drawing works, but also really slows down large cities (to the point where hovering over a business in my capital causes 2-7 seconds of lag, depending on building); I'm sure some of this is from drawing in a city with 356 people and 32 nobles, but it also means that I will not be expanding my capital any further!
And speaking of minor bugs, the game resets all settlements to 100% satisfaction on load.