I have the same, usually weekends when I don't have anything much to do (and it's raining so I'm not particularly motivated to go outside). I assume my level of physical and mental activity is much lower than a normal work day or active weekend/holiday day which is what produces the continual high levels.
When this is going on, if I have to go out when I wasn't expecting it, I find my blood sugar immediately drops, which is what makes me think it's down to energy consumption rather than stress/illness/etc.
Of course it's not always the case so I tend to wait (reading a book or the paper, or whatever I was happily doing) expecting it to come down, and eventually realise it hasn't and that I then need to do something about it like force myself to go and get wet for a walk or a bike ride (though I bought a turbo trainer for general winter fitness and 30min blood glucose "fixes", which was a really good investment).
I have to be a bit careful to do that before I start adding correction bolus to the mix as otherwise I'll immediately go low once I start activity.
Today isn't one of those days, despite the weather being terrible and my being sat typing on the PC and then expecting to watch the Coronation with my children, so time for me to go and eat something (or should I be thinking about popcorn for the main event...?).
Good luck!