I wasn't going to bother reporting this, but it happened twice within the hour. After fighting, I'd move extremely slow. Sprinting would actually cause me to run even slower. My mount was slower than 0% riding training. Nothing fixed it except logging out.
Then after taking a resource I was slow again. I have no idea how this is triggering, but it seems to be right after combat. There's no debuffs in my character sheet at all, and the only way to fix it from what I can tell is by logging out and back in again.