High platelets in child?

My kids is 6 years old and has been recovering from a stomach bug. They checked his CBC/glucose which was fine but his platelets were like 850.

Previous readings had been fine. Pediatrician said it's probably nothing to worry about and recheck it. Said it could be the machine or just reaction to the virus.

CBC seemed to denote it was viral. Blood flowed from his finger fine too in the fingerprick.

Most sites I've read said kids usually have high platelets as a response to infection. So is this worrisome?