NEW YORK—During a crowded rush-hour subway ride Monday, an inadvertent brushing of one human being's hand against the forearm of another elicited a swift, contrite apology, subway sources reported.

"Whoops—sorry," said proofreader Heather Wright, 32, immediately following the intrusion into 20-year-old Hunter College student Chris Franek's personal space, which occurred as Wright tried to turn the page of her book with one hand. "Sorry about that."

Responding to Wright's apology, Franek almost inaudibly mumbled, "It's okay."