Maybe it has now becomes ONE BUMP PER DAY (DATE) or maybe that is what it always was and it isn't clear rather than once every 24hrs as noted in rules? I even had one marked as BAD when the mod actually deleted it.
It is unlikely that it was always per day and not the 24 hour period and the rules haven't been changed recently afaik. Time zones are quite different and working out when the day starts would be a hassle, also the time gap is pretty clear to avoid bump spam.
My best guess would be an error on the part of the moderator(s) handling your reports.