You know.....from experience of my own German Shepherd (is this what Luke had)? I can fully believe that the dog may not have picked up on Jodi's scent on the way up the path,but did so on the way back. My shepherd is often too excited on her way out for a walk to notice anything,just pulls me along in the direction of the fields.However,on the way back when she is a little tired and by now has slowed down,she has the time to notice more,if that makes sense? Also,wouldn't the direction the wind was blowing have an impact? I understand that Luke's dog was not a trained sniffer dog?