Paying It Forward

I've spent all of this year travelling back & forth to hospital visiting my Dad after he had an accident a couple of days before Christmas.
It's £3 to park each time at the hospital, or you can get a 10 day parking pass which works out at about half the price, so I've been working my way through parking passes.
After having used my newest pass just twice it turns out that my Dad is being discharged and I have no need of the new pass any longer.
The other visitors I'd seen around the ward weren't about when I left so I couldn't pass it on to them so I resigned myself to carrying it around for the foreseeable future until I'd had cause to visit the hospital a further eight times.

When you have a pass you have to have your parking validated at main entrance, so as I queued for this I overheard that the couple in front of me had exhausted their pass & would need a new one the following day.  
I waited, got my validated ticket and chased after the couple and called to them, when they turned I handed them my pass.
They looked suitably confused and I explained my father was being discharged tomorrow and I no longer needed my pass.
"But you've only used it twice!" said the lady "you could use it again!"
I explained "it'll take me forever to use up the remaining 8 allowances".
"Well would you like me to give you some money for it?" she asked, going for her purse.
"Absolutely not, I know what a long slog it is going back & forth, that's my third pass here and I've been travelling back & forth to various hospitals since just before Christmas, so I know how expensive it is too".
She looks at me and says "I'll be sure to pay this goodwill forward, thank you so much"
I tell her that she's very welcome and she replies that she's very moved and is clearly a little tearful.
I wish them both well and say that I hope whoever they're visiting is soon feeling improved.
She thanks me over and over and tells me that they're visiting her father, which seems wonderfully serendipitous to me.

It was such a tiny gesture, but it left me feeling really good. 
I walked back to my car with a spring in my step!