It could be random, but I'm inclined to think that it occurs if you enter the vtech gate and head south too quickly, it considers you to be retaking the world map grid instead, but as I said before i have been in a couple of situations where my friends just walked on to it and teleported and I got stuck, and times where my whole team gets stuck there.
It's made doubly annoying by the fact it isn't my gate and quick exits from the area are its main purpose... Well that and occasionally hunting blue geckos.