This happens to me a lot. Of course, I start trying to figure out what I should have said immediately, though the conversation does play itself over in my head involuntarily over and over again. The worst part is, most of the time it's conversations with people that I will never speak to again in my life, or the subject matter is one that will never come up again. Most people in that situation would think, "At least that means I won't have to worry about it again." I, on the other hand, think, "That just means it will **never be resolved**." Then it does pop up in my head years later and I feel a wave of embarrassment over it. Hopefully I'm not in public at that point, or I'll have to have yet another awkward conversation where I try to explain myself, say the wrong thing, and then get a new memory that will repeat itself indefinitely.