A couple times I can clearly remember dreaming something that happened at a later point in time. What is that?

It has never been anything really important. the one i remember most clearly is when i was a young kid i dreamt that i was in cl and i got up to sharpen my pencil and then like 3 years later it happened exactly the way it happened in my dream. The wierdest part is i knew that i had seen it before but it was like i couldnt stop myself from doing it the way i remembered. I'm not worried just curious