That did not happen to me at UC Davis, no. I was much less aware of what class people were in in college than I was in, say, high school. Maybe because there is a much starker difference between a 14-year-old and an 18-year-old vs. the difference between an 18-year-old and a 22-year-old. I was the only freshman in my first upper div linguistics class; no one batted an eye other than the professor showing some sense of being impressed.