ST. PETERSBURG, Fla. — A woman started an act-of-kindness chain that lasted for hours at a Starbucks drive-through in Florida.

She ordered an iced coffee around 7 a.m. Wednesday in St. Petersburg and asked to pay for the caramel macchiato for the stranger in the car behind her. He returned the favor. The chain kept going and employees began keeping count.

The Tampa Bay Times reports the chain finally ended around 6 p.m. when customer No. 379 pulled up and ordered a regular coffee. Barista Vu Nguyen leaned out the window and explained the chain that started earlier in the day, asking if she’d like to participate. She declined, saying she only wanted to pay for her coffee.

Nguyen says he doesn’t believe she understood the concept of paying it forward.