This book has "war stories," where he describes the problem he was faced with and his different approaches before finding his awesome solution, so that's probably what gives me that feeling. But additionally, maybe I'm a freak.

I think this is just a personal thing. kinda like some people immediately spill their brain to some cache (whiteboard, pen/paper) and others stare at a wall for minutes then write when they have a fuller thought.

If it's a technical book I probably read and enjoy it and forget most of it. If I see a similar problem it might jog my memory and then I can refer back. Only works for good books. Its a different experience than directly interacting with the examples by coding/working out yourself.