Is it? They state they've funded 5000 companies since 2005[1], and if that was evenly spread per year, that's about a company a day. Maybe pg only pays attention to the ones that other people bring to his attention given that amount, and maybe he "knew" about OpenAI in that it was in some report he skimmed or was mentioned but maybe it was seen as entirely handled since it was a project for someone else there. It could entirely have been out of mind within a week or two of him "knowing" it and then it's quickly forgotten, and may seem like new information when it comes up years later.