It is most definitely OK!
Last year we were scheduled to go to DL for my son's 3rd birthday, but we had to postpone the trip just 2 days before when DH was hospitalized.
We rescheduled for late September, which happens to be a matter of weeks away from ALL of our other family birthdays and anniversary.
So we scheduled a day and Goofy's Kitchen meal to celebrate DS6's birthday, which had actually been 4 weeks before, and a separate day and Lilo & Stitch breakfast to celebrate DS3's birthday (which had been 4+ months before.) That way each boy had his special day, and the CMs were great!
At first I felt silly about DS3's birthday celebration and was overexplaining to people about our missed trip, but they really don't care! They just want to see you enjoying yourself.
This year we'll be going during my birthday, which I normally don't get too excited over.
However, I fully intend to wear a birthday button and enjoy a fabulous Disney birthday!
