Carol Flynn of Sioux Falls, South Dakota, didn't know anyone was watching when she paid for diapers for the Walmart customer ahead of her.
Flynn, 73, also had no idea that another customer caught the random act of kindness on his cell phone on Sunday night, only to share on Facebook what would become a viral video.
"I was standing in line and there was kind of a hold-up," Flynn told ABC News. "I’m not impatient in my older days, but I noticed this young lady was standing at the checkout. I walked over to her, put my arm on my shoulder and I asked, 'Is there a problem?'"
The young lady said, "I’m just buying diapers."
Katie Kanefke, a mother, learned that Walmart would only match the price of one set of diapers.
Flynn noticed three boxes set aside. "I said, 'You probably need those.'"
Flynn, a former state director for the March of Dimes charity, said, "Diapers are for babies and babies are on my heart. We’re always concerned about moms and healthy babies."
As Flynn tells it, "[Kanefke] said, 'You don’t need to but thank you very much. I have one little boy and he sure goes through diapers fast.'"
"I said, 'I’m sure he does," Flynn recalled, as she bought about $120 worth of diapers.
Kanefke could not be reached for comment today, but she told the Argus Leader, "I couldn't believe it. I was shocked. I kept saying thank you and God bless you...Then I walked out in the parking lot and started crying. It just hit me. It was an awesome statement of what God's love does."
Kanefke is a stay-at-home mom with a four-month old son, Marcus, the Argus Leader reports.
Flynn told ABC News the growing attention since Sunday has been a bit "embarrassing," and her phone has been "ringing off the hook."
"I’m just not afraid to talk to strangers. It was not unusual to go up and talk to her," Flynn said.
Jason Yoshino, the Walmart customer who captured the moment on his phone, said he was just perusing Facebook while he and his wife waited in line.
Yoshino said Kanefke seemed "very grateful."
"She kept thanking her. I think she was just more stunned than anything. When people are in that moment sometimes they just don’t know what to do," Yoshino said.
Yoshino, a wedding entertainer, already had about 4,000 Facebook friends and about 500 followers. But he said he did not expect the video to attract so much attention from strangers. Since posting the video on his Facebook page, he now has almost 300 friend requests.
"I always try to inspire people to do better in life. I deal with wedding people all the time. They’re fun loving events. I try to spread some love," he said.