Can poblano peppers be randomly spicy?

My fantastic fiance made us chile rellenos last night, and I encountered three bites in two different peppers that were really, really spicy. The rest of both peppers tasted totally normal. My fiance sampled the same two peppers and felt no bite. He put nothing spicy in there – just cheese, corn, rice, and then the tomato sauce on top. I’ve had the dish many times in the past as well as poblanos in other dishes, and they’ve always tasted earthy and slightly sweet, never spicy. They’re low on the Scoville scale, just above anchos and sweet reds. I can eat jalapenos no problem, and they’re way higher on the scale than poblanos – but those three bites were way hotter than any jalapeno I’ve ever tasted.

Has anyone experienced this with poblanos? What the heck was going on with those peppers?