Baby's eyes rolling

My child is going to be a year old in few days. On Feb 9 my son had fever off and on for that day only. Next few days he had flu (mostly recovered now). Recently I've been realising his eyes rolling backwards like the baby in the link below at random timing (after waking up from sleep and during activity time). Is there anything that I need to be concerned? #1stimemom #firstbaby #advicepls #pleasehelp https://youtu.be/5y6eCcSNAho