[bentcorner]

That's kind of weird. I see "may contain" all the time for other allergens and it's pretty accurate - it's a crapshoot whether or not I get an allergy (it seems m&m's warning is very accurate, whereas my local deli it's more of a cya statement). If I don't see "may contain" it's also safe to eat.

There must be something different about sesame and it's role in the food pipeline that makes it harder to deal with compared to other common allergens.

[bombcar]

I think the permissible "may contain" is the "this product was produced in a facility that also handles tree nuts" kind of warning, which is not technically an ingredient.