I'm glad he is OK. Keep a close eye that he does not have a biphasic reaction. Do you have epi-pens on hand, just in case?
~~~
I'm not sure where you are, I assume Canada or US. Neither country requires any kind of "may contain" warning and neither requires a bold CONTAINS warning either. Some companies chose to add it. I've been caught a few times thinking a product was safe. Fortunately, someone in the family reread and noticed "sesame" somewhere in the middle of the ingredient list.