If you initiate an attack on a tower with your pet, the attacked guild does not get a message until the tower in question goes down - at which point the owner of that tower is notified. If the majority of people in your guild happen to be offline, you may not have a clue as to what's going on until half your base is in ruin. Several guilds have already fallen victim to this.
It's simple, it's lame, and it needs to be fixed - imho.