Tweet only seems to post one time per content page, can't re-tweet from same page

I was in a Drupal content page (in this case, a story page) and posted a tweet by entering text in the twitter field, and clicking Save. I received the "Successfully posted to Twitter" message along with the message indicating that the page had been updated. The text posted to twitter immediately, as expected.

I then decided that I wanted to update the tweet from the same content page, so I repeated the process, and again, Drupal indicated the "Successfully posted to Twitter" message, but this time (and in subsequent attempts), the text did NOT post to twitter from this particular page.

However, I COULD post tweets using the same procedure from other content pages, so the mechanism seems to be working fine ONCE, but the behavior I'm experiencing suggests that you only get one shot at at posting to twitter per article in Drupal. If you want to re do the tweet and send it again, it doesn't post to twitter, even though Drupal indicates that it does.
As this behavior doesn't make much sense, I assume it must be a bug.

Running a cron didn't fix it
Logging out and logging in as another user didn't fix it.