Embarrassing revelations

Have you ever had a moment where you suddenly realized something, and then the next moment felt embarrassed for not realizing it sooner? For me, the embarrassment is usually because what I have just realized is probably common knowledge. For example: for years, I thought it was highly ironic that a handbook for grammar was entitled "The Little, Brown Handbook", which is, of course, an improper use of commas. However, just yesterday I realized that there is a company called Little, Brown, which, I assume, publishes the Handbook. How embarrassing!