I got lucky in never "bending" to the task of reading because I had to, just reading the school curriculum books if they were interesting to me. And I enjoyed reading greatly. But some books Ichose to read I slogged through and could not enjoy them because of my lack of maturity and perspective. Revisiting them revealed a lot more depth. And my reading of them grew with my understanding of the world. So I guess the experience is normal. And I wonder if I did not slug through those books at that time if I would have ever reached the insight I had on subsequent reading.
I am certain things from a good book stick with you, even if you don't recall it explicitly. It just lingers there in the back of your head, like bricks that are piled up on each other until you don't see them anymore but you do see the wall they form.