I walked in on my parents having sex accidently

When I was nine years old one day I was just playing outside.It was a hot summer day.I was just a bored and innocent kid.I went inside the house opened the door of our room and there I saw my parents having sex on a couch.My parents were both completly naked without any covers my dad was on top of my mom.I just stood there like frozen.I was shocked.It took them like five seconds to notice me.They stopped got up and rushed to pick up their clothes from the floor and put them back on so quickly.They didn't really say anything to me.It was so embarassing.