It really is endearing to see someone care about the details. It has lasting effect, not on everyone, but on many. It makes a difference in reputation, which definitely affects not only future return visits but in word-of-mouth.
Are we talking about one napkin? No. We are talking about the cumulative effect of special experiences and attention to detail. Nothing can beat that in word-of-mouth repution.
These probably are temporary cups, and maybe the same for the blank napkins -- ones supplied by the vendor on short notice. But that in itself may indicate a lack of planning.
I had a friend who owns a small local business (trash hauling) who built it from the start with her husband and his pickup truck, and now has 3,000 customers. She built her reputation on attention to detail and customer service -- they would pick your cans up from the backyard if asked.
She was once at an Olive Garden with me twice in the same month. The first time, she ordered coffee and the restaurant was out of sugar packets. They told her that the truck had not come in yet, with the sugar packets. She asked didn't they use sugar in the kitchen, and they said yes. They were surprised when she expected them to bring her sugar from the kitchen's supply.
The next visit, they were out of the vanilla ice cream on the featured dessert. She was again told that the truck would not be in for another few days with more ice cream. She asked the manager had they considered going to the grocery store in the same shopping center and getting more vanilla ice cream, and he reluctantly said that they had actually aready done that a couple of times. She said it was time to do that again! (They did, and she got her dessert, exactly as it was featured on the picture on the big ad.) She stopped going to OG for a long while, though.
The point is, while things happen, the attention to detail, both in planning AND in service or execution go a long way. The little things matter. Everyone makes mistakes, and sometimes you have to accept something lesser. But both then (how you respond to a problem) AND in the planning (like making even the napkins special), the little things make a difference in reputation... and affect the bottom line.