“You looked it up!”

I just committed a microaggression while guest lecturing in a class a week ago. I was covering for another instructor and using their slides, and I didn’t know what they meant by a particular term. A student asked and I gave them my interpretation but said I wasn’t sure if that was exactly what the professor meant. A female student raised her hand and said something like “it means this” and gave a definition. We were in a computer classroom, so I assumed she had googled the term and I said something like, “great, thanks! You looked it up.” Her face flashed a weird look and I realized I had just insinuated that she couldn’t have known that without looking it up, and perhaps because she was a woman. This occurred to me after I had moved on to the next topic, and I didn‘t know how to go back and apologize or correct my potential misperception without being really awkward in class. I don’t know the student’s name, so now I just have a horrible feeling in the pit of my stomach that I contributed to her feeling unwelcome in science classes at Davidson.