I think I was just confused that the date stamps in the different panels mean different things. Probably I created an empty note initially and that made a creation date that didn't line up at all with when I added the content.
I have a couple of consecutive entries entered exactly one month apart: 05/09/2017 and 05/10/2017. In the view panel they are dated correctly, however in the preview panel they are both dated 05/09/2017. If I change the sorting to be something other than by date, the error goes away but returns when I revert.