Here's a screenshot of my 404 log showing the most recent URLs to get 404 errors and the number of hits on each one. As you can see, they are related to the parent theme and all these started showing up after the update. Also, the user agents are both Windows, Mac, and smart phones.
Image: https://drive.google.com/file/d/0B4mnNZ1F-EDsT1BaeUtmZHB5OHM/edit?usp=sharing