It's not unusual. A few kid's birthdays fall in that range that it happens - and it is about the end of the school year. Lets not jump to conclusions like CBS or Newsweak.
My brain is still at the beginning of the school year. Seeing how it's nearly June, if she just recently turned 18, that would explain it.
I guess my daughter's friends came to mind... most of them have had to repeat a grade. Or two.