Nut allergies

Just this Saturday, my partner and I took the boy to our favorite breakfast place. We decided to order a dish that contained pesto and mushrooms. We had been given the okay by our ped to try mushrooms, and I figured pesto was rather innocuous, right? It contains basil, cheese, garlic, and olive oil. He has had all those things. As I gave him a mouthful, I thought back to the one time I made homemade pesto...about 20 years ago. It contains pinenuts. What the hell was I thinking?