I had hibernated my laptop using
and then woke it up some hours later to quickly check a document. I re-entered the above command and it worked without requiring a password. I assume this means that the sudo timeout is working from a relative time that is only ticking when the computer is awake, rather than an absolute system time.
I would prefer not to have sudo work without a password when I haven't entered it, in real terms, in the very recent future. Is there a way to enforce the timeout to not carry over like this while the system is in hibernation?