This is embarrassing... Under the Boot tab, if you scroll down there's an entry for Secure Boot. In there, I found the options for Secure Boot Mode and Key Management. I went into Key Management and reloaded the default keys, that turned Secure Boot State to Enabled, and when I loaded up Win 8.1 there were no more notices about Secure Boot!
So in a nutshell, it took me three days to figure out I needed to scroll down... Sheesh!