/ck/ - Food & Cooking

>go to supermarket to pick up a nice thin DiGiorno Pizza, some Funyuns and Red Bull
>on a whim, decide to do something nice
>pull out a small notepad from my bag, a sticker sheet and a pen
>write a short letter thanking the supermarket, the manager and all his staff for always stocking yummy foods
>put a red smiley sticker on the bottom of the page because the store's logo is red
>have no envelope, so I just fold it
>make eye contact with the cashier as he finishes checking my items later
>hand him the folded letter
>"Please, give this to your manager. It's very important"
>he just fucking opens it then and there, looking very confused
>become shocked and a bit angry
>hurriedly leave before I can parse his reaction properly
>haven't been able to go back since (it's been two weeks)
Did I fuck up?