Do you think it is possible that she stepped on something sharp or unpleasant or maybe something bit her and she associates that part of the lawn with something not nice? When we had Megan limited to just one room by baby gates, Austin bumped into them a couple of times and once or twice they fell over and scared the daylights out of him. Since then when I put my hand on the gates, he jumps or runs away. He does not like them. Maybe there is a garden troll out there scaring Suzi!