Ok I genuinely have no idea whether I'm right or wrong, and whether I should butt out or not? 
I bought some chips from my local chippy tonight and the guy behind the counter (one of the owners) asked me to pop in tomorrow when I'm passing, to give him feedback about the chips.
He said they're now using a new oil ( peanut oil ) instead of vegetable oil and wanted to know if it made the chips taste better or worse.
I said yes no problem...but then I had a thought and said "I hope you're telling all your regular customers about this, incase they have a nut allergy?"
He said, "No it's fine because it doesn't have peanuts in it, it's just the oil"
So I said, "Yes but if you're allergic to peanuts it can be deadly"...I then went on to explain how peanuts are banned from the local school etc and told him to Google it...because he didn't seem to be taking me seriously.
He then laughed and said, "Maybe I should put a sign in my window?" ( he so didn't sound serious though ) so I said, "Yes you should...and one behind your counter too". Then on of his timers went off so he went to the back of the shop, leaving someone else to take my money.
I know it's down to the allergy sufferer to check these things, but this chippy has used vegetable oil since before I lived here (and I've been here 19 years) so I wouldn't necessarily expect them to check every time they buy.
So ( since I really don't know much about peanut allergy ) WIBU to nag him tomorrow if there's no sign up? Or am I totally wrong and there's nothing to worry about?
The chips were lovely btw 