I love that part, because it shows you that you can interact with more in the world than was typical in games at the time, without feeling like a tutorial. It fits organically in the story, and enhances the feeling that you are in a very authoritarian society. That's something I've always enjoyed about game design with Valve. They allow you to feel like you are figuring things out for yourself, while ensuring you know the core concepts before you move on. A similar thing happens right after you get the crowbar, and have to break thru the boards. They use this style again when they introduce the barnacles, by having a bird fly into them and show how they work before you are in danger from them. This article goes into a little more detail on how that is done: Untold riches: The brilliance of Half-Life's barnacles.