In case your theme uses special styling for comments made by the author of a certain post or page you might have noticed that even if you’re logged in or provide the exact eMail address that’s associated with your profile WordPress doesn’t identify you as the author of the current post or page and doesn’t set the user id of the comment correctly. Instead of figuring out why this happens I’m using a simply plugin that fixes this issue.
Download the plugin, install it and activate it. As soon as you’ve done that the plugin will run on an hourly basis with WordPress’ cron mechanism, fetch all users and make sure that comments with an eMail address equal to the one from the current user has got the correct user id set. This way themes will be able to identify whether a comment was made by a registered user – most of the time this is used to style the comments made by the author of the current post or page in a slightly different way so they can be easily spotted.