Gave it a bit more thought, and I have a theory.
The day of Spring Daylight Savings is the only day in the year that's less than 24hrs due to the time change, so that might be conflicting with some sort of preventative measure preventing folks from claiming daily rewards more than once every 24hrs.
If they log in right after midnight the day after it'd still be within 24hrs real-time of the previous midnight, so they wouldn't get marked off for a new daily reward, but it'd still internally mark off that they'd logged in already that day so they couldn't claim one later.
Or it could be a problem with the daily reset script being run twice within 24hrs, since the midnights before and after the time change are only 23hrs apart. The calendar might not be properly recognizing that the *date* has changed after the day of Spring Daylight Savings ends due to it not being a full 24hrs real-time since the last time the daily reset script was run.
Anyways, whatever's happening internally I'll bet it has something to do with the day of Spring Daylight Savings being only 23hrs long, and that's somehow messing up the daily reset that runs the midnight after the time change.