Something about the map

[WhYdOyOuThInKtHaThApPeNeD]

Just a totally minor observation but curious if anyone knows something about it.
When bringing up the map of a continent, every now and again one of those little icons of a house with an orange roof that designates a 'building' glistens over with a bluish sheen. It's just a tiny little effect. It happens consistently every few seconds apparently randomly. Does anyone know if that means anything?

It seems odd that the programmers would be like, "lets make one of those little houses glisten over with a bluish sheen just for fun". There must be some meaning behind it. Or maybe it's just an effect to give the map some subtle life.