Is this the thing from 17 days before when he forgot to authenticate his update before getting on the plane, so he couldn't save the strip until getting internet again, causing a missed day?

I believe so. In that strip, he mentions getting on a plane for Taiwan and the beginning of this arc mentions "just the other day".

The only reader-added tags as yet are "Happens a lot" and "It's just one thing after another".

That kind of bullshit is why I haven't updated past 1.5.4.
After that version, you get some bullshit cloud version, and you can no longer add mods, you need to buy them.