I've noticed that when I take a break from the game, and come back several hours later, and attack NPC's, I gain a medal in one of the first few NPC's I attack. This seems to happen consecutively every time after I take a break, and come back several hours later.

Does anyone know if there's some sort of timer where after a certain amount of time passes, you get a medal from the next thing that you attack? Or has anyone else experienced this?