this is sort of a newbie question, but i'm not a newbie...

[chimak111]

IIRC, when installing Google Chrome or Opera "from the website", both offer the choice of adding their respective ppas so that the user can receive subsequent updates. And the choice isn't buried in fine print.

[przxqgl]

That looks like the installation adds a repository. Have a look in /etc/apt/sources.list.d/opera-stable.list.

that would explain why the updates came from a repository...