You are correct that the pumpkin looks to be in focus. In AF-s the camera should have refocussed between each shot. But given how the lady is left of center, is it possible that you had the focus selector centered, which would explain why the pumpkin in the middle is focussed in each shot and the lady is further out of focus with each step? Also, you didn't mention how you had the focus point selected. Was it manually selected by you, or did the camera select which af point to use?
Next time you might try selecting the af point yourself, and shift it left of center to the lady's face. Put the mode to AF-C and let the camera follow focus on the walking model. I use this method to photo cross country runners who are moving right along, it should work like a charm for a person walking.
Good luck and don't get discouraged. This autofocus voodoo takes some practice to get sorted out.