The reason the CEGA Gmail app prompts the user, on their first login, to enter native NetSuite credentials, is to establish a NetSuite web services connection. This connection is used when NetSuite records are viewed/edited in the app.
We resolved Curtis' issue by having the user sign in the first time with native NetSuite credentials. This creates the connection on our back end. Subsequent logins shouldn't prompt for these credentials and should auto complete as long as the user is logged into NetSuite in a separate browser tab.
Post this first login, the NetSuite Admin can update the user's login to SAML only. This, however, can possibly invalidate the established connection and can lead to loss of view/edit NetSuite record functionality. All other functionality should continue to work as is.