This happens to many of the characters. I’ve popped in and found Burns walking around way far away from the metal processing building where was supposed to be in. But before I could get to the building to check, he ran away much quicker than usual and when I finally scrolled over to the building, he was there already. I’ve seen characters wandering around instead of being at The She-She club, but when they noticed I was watching they raced back.
I think they get bored hanging around the same place over and over again. So they pop out to see what others are doing.