I'm halfway through Sorcerer's Stone. This is the first time that I re-read it and there are a couple of things that struck me that I had either forgotten or that I didn't notice the first time I read the book those years ago.
First of all, Hagrid arrived with the baby Harry on a motorcycle he borrowed from Sirius Black. That name would have not meant anything to me when I first read the book so I didn't remember that at all.
Second, Hagrid was knitting on the train when he was first taking Harry to Diagon Alley. I didn't remember that either.