The file wxall.plaintext.php sets the value of the “Updated:” time from the timestamp of the file $plaintextfile (which is your plaintext.txt file) that is set in wxall.settings.php. The behavior your page is showing makes it appear that the timestamp of your plaintext.txt file is continually changing. Can you check the timestamp a few minutes apart to see if this is the case? I could see this happening if you had a program that was constantly FTPing your plaintext.txt file to your website.
Steve