Scenario: You attempt to comment on page n by rightclicking and using the comment function, while you are scrolled so far down, that page n+1 is already displayed as your current page.
The Result: You create a comment marker on page n+1, however it is located in the same position that you had selected on page n.
This is obviously not intended and probably a result of generating the page position of the comment by checking the "current page" of the document instead of using the page that was actually right clicked on.