Well, yeah. I mean, I've actually been in this scenario, minus the guy staring at everyone. Or maybe there was a guy and I just didn't notice him there.
I had what was definitely a UTI. I was in agony all night long with it. I went to the emergency clinic first thing in the morning. I sat in the waiting room for 45 minutes in pure agony. By the time it came for me to see the doctor, the pain had subsided. Just like that. But I went for testing anyway, and turns out, I still had the UTI and it had begun moving into one of my kidneys. If I had gone home thinking I was cured, I would have been in a world of trouble.
People come and go in waiting rooms all the time around here. Some get up to stretch their legs, or go for a smoke, or wait in their cars, or whatever. I wouldn't find that very strange either, I don't think.