I have noticed that as well. There is one room that after you clear and are usually walking out with the team that out of nowhere comes one last soldier. Usually one of us gets attacked and then we see him behind us. I find it funny for the most part cause its like a momment of shock and then bam everyone goes nuts on that little guy!!!!

I have also seen in other dungeons where we will clear every room get to boss and no boss go back to almost the begining and have to clear an entire room all over again! I thought that one was just me...