Prospective student uses my first name in email. Encourage professionalism or eat some humble pie?

I have a student who is interested in joining my lab. I'm a brand new TT faculty member fresh out of a postdoc position. This student is currently an undergraduate in a neighboring department, but was encouraged to reach out to me when they expressed interest in pursuing grad school. Our first in-person interaction was fine. They told me about general background and interests. They were professional and I told them that we could meet again after the winter break. When I emailed to set up a time for a second meeting they responded quickly, but used my first name. I'm not so high and mighty that I demand people call me professor or doctor, but this seemed a bit unprofessional. Now I'm not sure if I gently correct it or just eat some humble pie and let it slide.