Some readers insist upon having a table of contents in a digital book, while other readers couldn’t care less. I originally published my novellas without a table of contents since I just read straight through, particularly on shorter works. It is possible that Smashwords automatically added one to those editions – their engine is supposed to do it, but I find it a bit unpredictable. If you bought the earlier stories from Amazon, though, they won’t have a Table of Contents.
From DECEPTION on, I included one in each story, no matter how it was distributed. Recently, I published new editions of the earlier stories in the Plume, with the table of contents. All of my books now have one.
If you like a table of contents and have an earlier edition of those books, chances are good that you bought it at Amazon. If so, just ask Amazon for the updated version.