Everyday hero

An elderly lady tried climbing the escalator stairs and fell back.
An everyday hero caught her. Protected her from falling back by absorbing her full weight onto his fingers and legs.
She was dazed. Shocked. But safe.
Walked off and found another old lady to tell her tale.
The hero... massaged his fingers and his leg. Winced. Limped off. No thanks for him and he didn't look for it.
What did he stop?
Not just one old lady falling back. But a whole domino of people falling back if not for his strong leg and fingers.
And none saw it but one.