That is a good first line. Actually, now that you've supplied that line, I want to modify my position, because I do very much like first lines that present a very bizarre situation right off the bat, that makes you want to find out what's happening. Especially ones that give you the premise of a story, right off the bat. I say "a story" because it doesn't have to be the premise of the story that's being told. For instance, it would be alright with me if the story for the line you quoted wasn't really about the grandfather at all. I'm trying to come up with lines like this, and the only one I can think of off the top of my head is: There's a man in the habit of hitting me on the head with an umbrella.

Meta ones can be great voice displays but I get annoyed if that navel gazing lasts for more than a few sentences at the start before telling me actual stuff.

I love the meta ones that are very direct, such as, "This is a story about the end of the world." I don't like the meta ones that are actually metaphysical, such as, "Existence is a strange thing."