Can't be entirely sure as the file difference tool has never worked for me but have had some readme.txt being reported as changed. Pretty sure they have not changed.
Modified plugin file: wp-content/plugins/yet-another-related-posts-plugin/readme.txt
Modified plugin file: wp-content/plugins/better-delete-revision/better-delete-revision.php
Modified plugin file: wp-content/plugins/avh-first-defense-against-spam/readme.txt
Modified plugin file: wp-content/plugins/meta-tag-manager/readme.txt
http://wordpress.org/plugins/wordfence/