I had the free trial version and successfully put some thumbnails on my websites. I noticed that when I first published the page an older version of my homepage appeared. I had published a newer version a couple of days ago before trying Thumbshots.  The following day it showed the current home page.

I then signed up for the premium account. I placed a larger resized thumbnail on a webpage and it is now generating a picture of a prior version of my homepage that was replaced several weeks ago. What is it looking at to find these old versions?