Customer I Almost Lost Because I Answered Too Fast

Someone sent me a detailed question last month. I answered in about four minutes, because I knew the answer.

They did not reply. Followed up a week later, no response. I assumed they had lost interest.

Then they told me, much later, that my fast reply had felt dismissive. It was too quick, too short, and they had read it as me not really reading their message.

My speed, which I thought was a virtue, had read as carelessness. I had treated their long carefully written message like a simple question, because to me it was.

I answer fast because I care. Some people read fast as the opposite of care.

Have you ever been misunderstood by being too efficient? And did you change, or did you decide it was their problem?