Issue confirmed - the trusted-key option in gnupg sets the given key permanently to be trusted, not temporarily as was incorrectly assumed.

I apologize! To remedy the issue, please clear the trust value of key with ID "DAFFB000" by calling

gpg edit-key DAFFB000

and then command "trust", set value to "unknown", save and quit. After that, the trust value should be "unknown". If in any doubt, restore your trustdb from backup.

Update follows soon.

Thanks, will check in the next hours.