This happened in Krok to with Manders suddenly walking on the corners. But i was used to this. i look around and see a pig suddenly walk up to the sidewalk and kept walking until i couldn't even see his name because he went underground! Many Ronin and pigs are clouding the sidewalk. even when tey are not on the sidewalk they still manage to grab me.
That's meant to happen in dungeons, what you thought they would be easy?!?!?! The sidewalk thing is either a bug, or a challenge in the game. It's always fun to try to time their walking.