At the end of the lab period, a student turns in their lab report, and then proceeds to ask a couple of personal questions along the lines of "Have you always lived in <name of city>?" Since the instructor is the one expected to maintain a proper distance with his or her students, would you consider it inappropriate if the instructor then asked "What about you? Where are you from?", potentially showing an interest in that student? And how would other students overhearing the conversation perceive it? Particularly, if both participants in said conversation were smiling and friendly with each other?