Are you sure you were actually asleep, you may have only been bordering on the sleep but not fully asleep at that point. If you are a restless sleeper then blaze may not pick up your sleep until you actually stop doing somersaults or jumping those fences with the sheep you're trying to count.
Check the setting on the app for the sleep is it set to normal or sensitive set it to sensitive if it is only on normal and it should pick up your sleep better.
