This has been my experience with Seamless Single Sign-On the newly available feature that I am pairing with the equally new Pass Through Authentication (PTA) in my lab....
1. Outlook Pro Plus is initially setup
2. The user is prompted by Outlook to save the credentials and user clicks "yes" (this probably reflects the saving of the creds to credential manager)
3. A user's password changes
4. Outlook continues to operate with no password prompt (from the existing ticket/token I am presuming)...
5. The user reboots and logs in to Windows with new password.
6. Outlook continues to operate until suddenly a password prompt!
Is this your experience with Seamless SSO and PTA?
Is this your experience with ADFS?