Why is it?

I found out registration for kindergarten is May 4th. My daughter is due in the next month or so for a follow up on her singulair. So I went ahead and scheduled her physical for school for today. I found out late Tuesday that my daughter's class is having a "dinosaur egg hunt" today. I found out this morning that it's just before she's due to be at the doctor. Why is it that as soon as you schedule a dr. appt. something come up (particularly for kids) at the same time? *sigh* I can only hope they finish it in time before I have to take her in.