Pam_unix(sudo:auth): Couldn't open /etc/securetty: No such file or directory

I’ve followed Linuxbabes build an email server from scratch up until chapter 10. For some reason, in my journal I am getting pam_unix(sudo:auth): Couldn't open /etc/securetty: No such file or directory.

Any idea what this means, if it is of concern, and what I should do about it?

Thanks Linuxbabe!