This year, the Passover cake meal comes with a nut allergy warning. Great, you need that for just about everything you bake. I ended up making a (much) less expensive substitute by grinding matzo in my electric coffee grinder. If I owned a food processor, I'd have used that.
Just a heads-up if you discover the warning at the last minute, you can still finish the cake you were baking. this is a real problem though. I know to stay away from the prepared mixes, but I really thought the staple ingredients were safe-obviously I was was wrong. A good lesson in remembering to read the labels of products every single time. Production lines change, as do ingredients.