What would cause elevated platelet count in a 13-month old?

My 13-month old son just had some routine blood work done and the the pediatrician's office called to say that there was evidence of an elevated platelet count (not leukocytes or anything else - just platelets). We're having that part of the test redone to check for errors and it might just be that, but what are the other possabilities?
- he has not suffered any notable physical injuries and does not show irregular bruising.
- he has had a mild cold which began about 2 days before the initial blood test.
- he has none of the other symptoms of Kawasaki's disease (fever, red eyes, etc).

Any ideas for my paranoid mom of the month crisis?

In answer, to the first resposne:
- he has no apparent symptoms
- I don't know the actual numbers, I haven't yet seen the lab report.

You don't mention how much the count is elevated, or if your son has any apparent symptoms. Its not unusual for an individual to have some blood parameter fall outside the norms, so if the RBC count is slightly elevated - there may be nothing wrong. So, I would assume that nothing is wrong unless there are some signs that your son has some sort of problem caused by the elevated RBCs. I have been very healthy my whole life and there several parameters in my blood counts that are always outside the norms - apparently, those norms are not normal for everyone.