I think almost every time I have tried to use the 'fresh bakery' in the supermarket (you know, all the breads and whatnot out for you to pick from) - someone has come over and started moving them around with their bare hands.
Not picking one up to take (questionable but tolerable), actually moving items on top out of the way to get the item they want. Customers this is, not the staff.
YABU - why not, you'd do it in the fruit and veg aisle
YANBU - bad manners