What rang for me on that link, is :

1) often these people don't have obvious symptoms. The gal I was searching for had a TIA and was hospitalized and they found the platelets then. She has a chronic health condition, and one would think gets regular CBC testing.

2) I do not believe the platelets are included in a standard CBC by ALL labs. They are in some. You can ask your doctor. And while you ask find out the exact number you tested at last... see if it is in a high normal range but not out of range, yet. A high normal might be symptomatic, just like a high normal MCV can indicate low B12. Not exactly out of range but getting there.