I love Cassey's planners, but this one didn't just miss big holidays. It also repeated numbered dates, messing up entire months on the calendars, so I would be confused as to what date it actually was. It unfortunately failed in its most basic role of being an accurate calendar.
These fit planners are a lot of money, but I like them so much that I have always tried to invest in them. Now, I'm not so sure if I'll drop another $30-$40 on a planner that I may not be able to trust when stores near me sell cheaper ones that are just as cute.
I would just suggest to Cassey that she do her best to investigate what caused this problem and to figure out how to prevent it from happening again.