[Plugin: WP to Twitter] 403 Forbiden

I started getting 403 error messages today when updating my posts.
Never happened before, so I wonder what’s going on.

I’m using version 2.2.8 on WP 3.1

Error Message:

One or more of your last posts has failed to send it’s status update to Twitter. Your Tweet has been saved in your post custom fields, and you can re-Tweet it at your leisure.

403 Forbidden: The request is understood, but it has been refused. This code is used when requests are being denied due to status update character limits.

Sorry! I couldn’t get in touch with the Twitter servers to post your new blog post. Your tweet has been stored in a custom field attached to the post, so you can Tweet it manually if you wish!

http://wordpress.org/extend/plugins/wp-to-twitter/