10-Hour 'Pay It Forward' Line Ends With Customer No. 458 Who Refuses Woman's iced coffee was free but next person had to pay up.

 -- A 10-hour stream of kindness ended abruptly at a Florida Starbucks Wednesday evening when customer No.458 broke ranks and declined to "pay it forward" for the next drive-thru patron.

"She got a free drink from the previous customer," Celeste Guzman, manager at the Starbucks on Tyrone Boulevard in St. Petersburg, told ABC News today.

"She was happy about that," Guzman said. "But she didn't want to pay for the next patron.

“It all started at 7:21 a.m. yesterday morning when a woman paid for her iced coffee and decided to pay for the caramel macchiato the customer behind her ordered as well,” Guzman said.

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For the next 10 hours, more than 450 customers at the drive-thru graciously accepted the kindness of strangers and then paid for the next customer's order.

"Our barista would tell the customers: 'Your drink has already been paid for by the previous customer. Would you like to return their favor and pay it forward?'" Guzman said.

But that all came to a halt at 6 p.m., when a woman pulled up in her white Jeep Commander and ordered an ice-coffee.

"She didn't want to pay for the next customer,” Guzman said. “I don't think she understood the concept of ‘pay it forward.’

"Sometimes customers can't pay it forward, because they can't afford the order.”

But the random acts of kindness began anew today, Guzman said, when one customer bought a $40 gift card for the next customer at the drive-thru.