Yeah, it usually doesn't do that, but it just so happened that after I made a bulletted list, I decided to put a borderline on the line immediately following it. Unfortunately I didn't realise the trouble it'd cause me until later ಠ_ಠ

It works perfectly fine on a new document though, so I ended up retyping it (which wasn't too bad since I needed to redo parts as it was). Oh well!