I have an elaborate blog post draft I’m working on called “Paying Is Not Punishment” and part of it addresses this feeling of “what should I do if, in certain unpredictable situations, I absolutely rationally don’t want to force myself to do something that Beeminder says I have to do”. Personally, my answer is “pay the pledge”. Commitment devices are powerful and you shouldn’t expect them to have zero cost. Sometimes you’ll pay when you don’t “deserve” to and that’s fine – it’s still worth it.
You’re paying in part to preserve the power they have the rest of the time. There are compelling counterarguments to this way of thinking, like not setting up a too-aversive relationship with Beeminder perhaps. Lots of debate and discussion ongoing!
A less extreme answer is “let it derail and reply to the legit check”. Fake data is never the right answer. [shudder]