The retune event was stored in your HDR-FOX in advance. The earliest this particular retune event could be activated was on the afternoon of the 23rd.
I'm guessing that you do not have the custom software disable-dso installed?
What probably happened was that when the reminder turned on the Humax the Humax presumed that you were there watching and displayed the invitation to stop the retune. It then went ahead and retuned and removed your entire schedule.