I was approaching the checkouts at the supermarkets today, and saw one with two people - one, a man, was loading his trolley having paid, and there was a woman standing there who I assumed was with him. I joined that queue and started getting my stuff out when the woman said "Excuse me, I'm first". I was confused and said "Come on, you haven't got a trolley", whereupon she gestured to a lad who had come up behind me with a trolley and said "There it is". I said "Yes, and it's behind me". She got into a huff and stropped off muttering "Don't panic, it's only a queue" to which I just answered "Precisely". I was perfectly calm throughout - if anything, I was just confused - and in fact was about to move myself rather than get into a stupid stand-off.
WIBU? Has reserving your place in checkout queues become a thing that no-one's told me about?