Oops ... temporarily forgot I'm a student

I'm taking some courses which are dual-listed for undergraduates and graduate students this semester. One of the classes is a bit more informal, a reflection of the professor (whom I adore!) who happens to be more of a free spirit.

Last week, one student was called to write something on the board, and I was asked to write the translation next to his work on the board. He'd used a blue marker, but the professor handed me a black marker, and I chose to use the one given to me.

As I wrote the translation, the professor was engaged in conversation with students on the side of the room furthest from where I stood at the board. When I'd finished, I began to walk back to my seat.

"Yo, you shoulda used that other marker!" One of the freshman called out to me, accusatorily. "That black one you can't see."

Without even thinking, I flipped into Teacher Mode.

"Excuse me?" I replied politely, channeling the Miss ************* TeacherVoice from my student teaching experience last year. "That was rude. It would be nicer to say 'please.'"

I traced my answer (which was quite legible) with the blue marker, capped the marker, and walked back to my seat in a graceful, elegant (and admittedly, a slightly haughty) manner. The freshman called out, "Thank you," and I merely acknowledged this with a slight nod- no eye contact. The professor was not aware of this exchange.

~*~*~*~
When I realized this later, I felt a tinge of shame. Was it my place to say something? I wouldn't talk to my peers like that ... but then again, my peers wouldn't speak to me like that. Is it inappropriate for me to not think of some of the underclassmen as my peers even if they are in the same class? Does that make me a snob? (I have a good rapport with the students here, especially those who know me through the ensembles. I don't think they see me as a snob. As they're getting to know me, I think most of them realize I am a very sweet, approachable person.) Did I respond in kind to the kid who called out to me? I mean, he publicly criticized my work but I publicly criticized his comment. Either way, I was surprised that I popped into Teacher Mode so suddenly. Even though these kids are the same age as my students from last year, it probably wasn't my place to respond as I did. Oops. So I'll try to guard TeacherMode a bit more from now on!