Costco door checker policy

I appreciate the fact that we have to sacrifice something (e.g., our time spent waiting in line) in order to get something back (e.g., lower prices). BUT Costco still needs to work on customer service and attitude-- perhaps especially in the door checker department. I just used my new Costco membership card for the first time today, and everything went great until I attempted to walk around the ten people with huge carts full of stuff, as I had only 2 small items. The door checker lady could have said any number of things, including simply directing me back to the end of the line, but instead she chose to mark off my receipt and insult me. Sure, the error was mine, but the "rules" of door checking aren't terribly clear (there is no velvet rope, no sign w/ instructions) and I'm sure this is a common error amongst the few folks w/ just one or two items. Costco's official policy seems to be to invite you into making the error, let you get away with it, but give you a stinging insult in reply. Definitely not how I would like to be treated.