Data loss when submitting rubric form after session time-out (rubric grading)

I have a homework that takes some time to grade using a rubric, and I've been bitten by this bug more than once. If the form is not submitted within a certain time (which seems arbitrary to me, since my university is using a single-sign-on cookie), the session key is no longer valid and I get the message "Incorrect sesskey submitted, form not accepted!"

The bug is the fact that there is no recovery from this situation and there is data loss (in a 12-criteria rubric with feedback it's painful).

Shouldn't we be asked to re-authenticate, and then have the form contents be properly submitted, similar to how it works when I try to access a page when I'm not authenticated.