And I’m so sorry.
This happens with me constantly, and has done since I was a teenager. Mostly at bookshops, occasionally at craft fairs, or anywhere that an author can persuade someone to let them set up a table. Once or twice, it’s happened in malls I frequent. It’s very often a self-published author, but not always. Most recently, it happened at a convention, where I had an amazing time…but I spent half the time skirting a couple of hallways like they were minefields, because they were full of such elaborate tables and keen to the max authors.