Open Mouth, Insert Foot

I have a friend (who will remain anonymous but she knows who she is) who has a contract to shovel various areas in the town on a regular basis. I know she has this job, and the other day I saw her outside of my house shoveling. I felt it necessary to go out and harass her for a little while, and then went on my way. And then last night, I was talking to her about this encounter and I said, "I saw your husband and another guy shoveling the other night as I was driving home our babysitter. Who was that?" To which she replied, "That was me." Right here is where I should have said, "Oh, really? Oh wow, it was really dark, I hardly recognized you. Sorry for the misunderstanding," or something to that effect. Instead, I replied, "No, no. I'm sure it was a guy." Really? Am I that clueless? Do I always have to let this quest to be right interfere with common sense? Then she said, "No, it was me. I was wearing a hat. And a big coat." Ummm.... pretty sure she knows whether or not she was out on a Friday night shoveling. So I'm wrong. I can admit that. But what about me persisting with this whole "It was a guy" thing? How does one backpedal from calling a woman a man? There is really no way. So I apologized and sent her on her way, hopefully not leaving any lasting emotional scars. I'm such an idiot.