I have the same problem with our electric alarm clock. Each spring it automatically goes forward one hour and in the Autumn it automatically goes back an hour. So far you might think all is well but it does this randomly ! Never on the right day and never on the same day or date from year to year. . . The rest of the year it's fine. As we seldom need to get up at a specific time we don't worry about it. Find it quite amusing in fact. Ghost playing with it ? Doubtful as we have moved twice since we first noticed the discrepancy.
I have a small bedside clock and try to get up just before 7am. Husband gets up at 6. I don't set the alarm. This morning I got up as usual about 5 to 7, got dressed etc, went downstairs. Clocks down there said 8 o'clock . The battery on my bedside clock was still working, I've been checking it all day. I accused husband of putting it forward an hour for a joke - he said no(?) Can you think of any other explanation?