I don't know about the sesame seed thing, I don't remember them but I don't
have to watch for them either.

Peter is generally safe with happy meals anywhere.  We have a policy where  I
or my husband check the burger for cheese before my son gets it.  We have
been accidently given cheeseburgers on a number of occations.  Also, if the
particular McDonalds is dirty or has obvious bad management, Peter either
doesn't eat there or eats only the fries and apple pie.

--Sally mom to Peter (allergic to milk, eggs, peanuts, peas, legumes,
chicken, tuna, green beans and walnuts)