I am not sure whether this is something that was already happening or if it is a temporary issue, but I accidentally noticed that many of my categories with dashes are pointing to a “Not Found” page.
Some examples:
Those links work for me. Could it be that you caught your site in the middle of a rebuild?
They are also working here now, but they were not down for only a few minutes. When I noticed it, I rebuilt the site myself a few times trying to fix it. They were not working for a few hours. From around 10:00am to 12:15pm (UTC 0), when I had to leave. In other words, it started working again sometime between 12:15pm pm (UTC 0) and now.