A Bizarre Clock Anomaly

When I got up this morning, I noticed that my battery-powered wall clock was off by 2 hours and 34 minutes. It had been showing the correct time the previous day. I thought to myself, "The battery must be losing power."  But when I timed the clock for 60 seconds, it seemed to be working fine.
I reset the wall clock at 1:00 PM to match the time on my cable TV.  For the next seven hours, the wall clock exactly matched the time shown on the cable TV, just as if there was no problem with the wall clock's battery. Somehow, inexplicably, the clock lost 2 hours and 24 minutes off of its time, even though there was nothing wrong with the clock's battery.

This is one of very many spooky events about my home which create the impression of some invisible power attempting to leave a variety of signs of its presence.  You can read about many such cases here.

Postscript: It has now been 24 hours since I reset the wall clock to match the cable TV clock, without replacing the wall clock's battery. The wall clock still shows exactly the same time as the cable TV clock. Clearly there was nothing wrong with the battery, which has operated flawlessly for the past 24 hours. So why did the clock lose 2 hours?