A cashier's act of kindness is resonating with Southern California residents after she invited a teen with cerebral palsy to help check out groceries.

Jeanie Robinson said she and her 14-year-old son, Andrew, had gone to the store like any other day Dec. 30.

It was a little quieter due to the holidays as they headed out in the pouring rain to the WinCo on Winchester Road. But Robinson said every trip to the store is different.

"Some days he doesn't like the store, and some days he does. Not every day is the same as another," Robinson said in a phone interview with NBC4.

This day in particular for the teen with cerebral palsy was especially good.

His mother said his infectious smile got others in the store smiling back as he pushed the cart along.

"Throughout the store Andy had this contagious smile. There weren't lots of people so when I threw the salad mix across the aisle into the cart he about died laughing," she said in a Facebook post.

As mother and son went to check out, Andy asked to load them groceries onto the conveyor belt.

The cashier, who Robinson believes is named Shaylene, then did something very simple - but amazing.

She invited Andy to scan the groceries. At first, Andy didn't move - until his mom said to go for it.

"It was so kind of her because so many people get annoyed with special needs kids," Robinson said. "But she had all the patience in the world."

Robinson shot a video of the kind exchange and posted it to her Facebook where it's been viewed more than 10,000 times.

The family, which moved to Temecula from Germany 17 months ago, hadn't expected such a sweet gesture.

Robinson said Andy is one in a set of twins that were born prematurely in an emergency C-section.

From the beginning, his mother was told the prognosis "wasn't looking good."

Doctors even told her Andy wouldn't make it. After three days, they said he would never walk, talk or eat on his own.

"In my mind, I said, 'What can I do to fight that?'" she said.

Robinson took him to all kinds of physical therapy and pushed and pushed, fighting to help her boy.

Andy has a limited vocabulary and walks with a limp, but other than that, he's as healthy as can be, she said.

Robinson is hoping the video sends a message to people when interacting with people with special needs.

"Be kind. Be respectful. And smile - nothing in the world is so bad you can't smile," she said.