Forced updates did happen (only way to play the game if Steam was aware there was one available - and God forbid you had a slow/flaky connection - no gaming for you today, not even through Offline Mode !).
Combined in at least one instance with the new version not being able to load the old multi-hours save, and no rollbacks, so hopefully you manually backed up the whole game !
(At least the devs fixed it in a patch after some days...)
I'd say if I have one big complaint about Steam, it's that it's update control needs work. I don't know if it's intentional or not but rolling back to an old version is...impossible? I'm vaguely aware there is an option to maintain the version you already have but I believe it's quite buried.
I've had updates completely change game balance, making character load outs I'd grinded up not work the way they did before. I've also had new linux versions break compatibility. This is understandable in multiplayer games, but I was playing these games single player.
Combined in at least one instance with the new version not being able to load the old multi-hours save, and no rollbacks, so hopefully you manually backed up the whole game ! (At least the devs fixed it in a patch after some days...)