Zangoose and Seviper have switched places!

Zangoose popped up in front of me on my cycle to work yesterday.
I was surprised to see it but later found Niantic had switched the region's for Zangoose and Seviper.

Personally I wish they would do more events like this. It gives people a chance to catch regionals they may not have the chance to catch otherwise.
But rather than them randomly pop up why not put a bit of story in there.
For example if plusle and minun were to change places the could make up some story about the earth's poles temporarily switching in some freak geological incident. (I mean the ensuing meteorological chaos may kill us all, but at least we'd get a new Pokémon 😛)

What do you think?