You would be. It's a slam dunk even. Producers have legal obligations. When they don't meat those legal obligations it makes litigation extremely easy. In the eyes of the law they were not duly warned.

This is my actual industry. This isn't some hypothetical. It's one of the main ways that enforcement happens. There's inspection, which is more or less significant depending on what it is, but for most foods they rely on consumer action for enforcement. This scenario is actually super clear cut. Just need to have damages so you can have standing.

And it has to be this way too. Otherwise all food would contain a "may contain" statement and all the relevant regs about labeling and controlling contaminants would be irrelevant. You can't magic words your way our of not having to follow regulations.