When editing a post, the links go through the automation process to make then active a_href links.  And after each edit the coding gets replicated.  So the original HTML link and the onscreen link gets a third version hidden in the code. (and a forth after the second edit, etc.)

This is only problematic when one post gets edited repeatedly and has multiple links.  Eventually you run into the maximum post limit.

Have been working around the issue by periodically just copying the text to some other program and back.