Thank you for trusting JustAnswer with your important question.
Schizophrenia is largely thought to be a genetic disease that is usually triggered into active symptoms in the late teens and early twenties. There is currently no test or treatment that can be done to identify and treat young children before they develop the disorder. Not everyone how carries the genes becomes Schizophrenic. Even someone born to two parents who have the disorder can still manage to not develop Schizophrenia.
What you describe could be from other disorders, including a normal part of your sons age. Sometimes it is due to anxiety
(such as in depersonalization or dissociation), sometimes as part of sleep issues (such as hypnagogic episodes or sleep disorders), or even part of medical problems (like seizure disorders) and can sometimes happen in kids who never develop the criteria for any disorder.
Your best bet is to keep an eye out for further symptoms, and seek a psychological evaluation if you believe the symptoms are happening on a frequent basis or if they are starting to cause functional problems for your son (such as disruptions at school, fights with peers, withdrawing from social activities, etc.). Until then, continue to let your son know that it's safe to talk to you about anything, and try not to panic
(hard to do as a parent, but kids pick up on our panic and can start to hide symptoms in order to protect us from feeling that panic).