I think the original header post is a no-brainer, meaning the situation is so clearly NOT an etiquette faux pas.
Now I give you what I think is a good checkout line manners discussion piece. This has happened to me twice in the last six months.
You are standing in the grocery checkout line, holding a basket with roughly five items. There are only one or two people in line ahead of you before the cashier, so it is a relatively short checkout line.
The person behind you has one item. You haven’t even noticed that, until…that person taps you on the shoulder puts that one item into your face and says:
“If you don’t mind I’m going to step in front of you because I only have ONE item. You don’t mind do you?”
Oh, and that person is no different from you, having no old age, or handicapped, or whatever special skip-ahead pass.
So would you say this person is deviating from what we normally consider good manners?