That's what happened to me earlier this February. For some reason, my tweets were not being updated to Facebook via the Twitter application anymore and I only found out at the end of the month.
To fix this problem, do the following:
- Log into Facebook and go to the Twitter application http://apps.facebook.com/twitter/
- Under App Permissions, you should see the following:
- Uncheck the Facebook Profile check box.
- After the spinning circle disappears, re-check the Facebook Profile check box.
- Send a tweet using your favorite Twitter client to test that your tweets are being posted as your Facebook status again.