Is the 个 required here? A: 我老师是个中国人

B: 我老师是中国人

I feel that A says ''My teacher is a Chinese person.'', and that B says ''My teacher is Chinese.''

But I feel that A carries an impolite nuance for some reason.

Am I interpreting this incorrectly or what do you think of phrase A ?
There is no big difference between these two sentences. 个can be deleted.