I just found what was setting the store alarm off. I have this old clipboard in the bag to stop it from sagging when there's nothing in it. I've had it for years, since way back when I was doing the professional writing course, and it's covered with all sorts of graffiti. It also has an old barcode sticker on it. The sticker is from one of the trade paperback comics I bought when I was living in Melbourne. I remember I kept it because it had lines of circuitry on the back, and I'd thought that was pretty neat. Of course, the lines were a magnetic strip, sensitised to set off the security at the store where I'd bought the comic. Stupid technology making a fool of me.