Grammar Nazis

I concede that I mistyped "ah", but you are incorrect with your second thought. My "but" was not at the beginning of a sentence; It was after an interjection.

You are mistaken; I am not taking grammar lessons. I am merely citing evidence to support my claims.

With the fact that "Ah" being its own idea, the "but" would be the start of a brand new sentence. Thus, "but" should be capitalized and you are not supposed to start a sentence with "but" or "and."