Metro Card lets me choose

I’m glad to have a chance to go out at working hours,even for business affairs. It is so kind of the Dept Manager to share his Metro Card even though I decline his favor. But when I punched his card at the entrance, it doesn’t work and turns out to be in debt.
So question takes place: Two choices of dealing with this matter await me:
First,to make a phone call to manager and ask whether add some money in, and then tell him the fact . Let him decide what to do next, of course he will pay the same amount of cash I paid back.
Second is to tell the manager the fact in an easy manner and let him forget it. At most, when he comes the sense to pay me back, I say: “Well, no big deal, u could treat me an ice cream.” And let it pass.
So which is right? Or no right or wrong?
Which is a better choice?