You are right in abstract, but it is kind of wrong to show off in front of an old lady just because she scowls at you… you know? Wouldn’t have been easier to just donate something to make her feel her service to the church is worth?
You say that you prefer your contributions to the parish to remain secret yet you take offense when someone else challenges their existence. If you truly want to be a quiet secret contributor then you should not walk off those who scowl you.
I have been scowled by old ladies in the church and I know how annoying that is, especially when undeserved. But I think that they are probably suffering from solitude, spiritual challenges, many things. Holding a grudge is not a way.
Making the sign of peace is a meaningful gesture not just a hand shake. If you two have quietly argued maybe next time, now that you have proven your self to her you can also bemuse her and put something in the collection bag?
Where is the peace in you still being angry at her even after you showed her you don’t care about her?