A couple of months ago I got my usual cobb salad at Pret a Manger, with a balsamic vinaigrette dressings. The salad has a gluten-free sticker on it, and the dressing always has been gluten free.
Well, I got almost immediately sick and hadn't been back again until last week. I picked up the cobb salad and went for the dressing and noticed that there was no gluten-free sticker on the rack card in front of the dressings. I looked at the label and it now has soy sauce in it (with wheat). In fact, none of the dressings are now gluten-free, I even e-mailed the company. So strange for a company that has gone out of their way to expand their gluten-free options these last couple of years.
Anyway, I don't know when they changed the dressings, but my reaction was so bad and immediate that time in September, I'm guessing that's what got me.
It's true what they say: You have to read the label EACH time.