Not entirely sure what went wrong here, but something did. There was a merge on the user account that somehow orphaned this question. I fixed that up, so the user should have access to the question once again.
In general, we (the community managersthe community managers) have the ability to (dis)associate posts, so feel free to hunt one of us down to do the honours. There are usually a couple of us hanging out in the Teacher's Lounge.