It’s not unusual for servers to attend to large parties during their shift. These typically involve families and friends celebrating birthdays, holidays, anniversaries, or graduations. Once (or a few times) in a blue moon, the reunion is for a depressing reason: burying a loved one. If a server asks about the occasion, it can affect the mood.
This is why one server urged fellow waitstaff to stop doing this after making that same mistake several times.
