i think you are reading too much into it personally. The shallow runs that allow duffus change all the time, a dog , beast or man walking across the area will cave in a load of the time, and rain collapses them as well. i dont think they can tell by moisture on the traps dripping. As for the traps filled with earth its surely just the mole moving his fresh dug soil to a "blowhole" ( molehill) to push out and i think its just coincidence. I mean when you set a trap you dont set it right next to the castle/ fortress you set it out a bit , this is where they are extending their boundaries , vis a