Years ago DS ate the Hershey's chocolate chips and refused more, swearing they tasted like peanut butter. He unknowingly ate them from the same bag weeks later and said the same thing. One of the 2 times, he broke out in a rash on his chin. Not sure if it was the chocolate, but even so, considering he's anaphylactic and asthmatic, it wasn't much of a rxn.
I called Hershey's and they said they could have picked up the aroma of the peanut butter from sitting next to them on the shelf. It was years before I was comfortable trying them again, but now I do. However, I note the shelf position and often sniff the bag first
I'm sure I get a few weird looks!