A few bites into his chicken burrito, his mouth was overtaken by a wave of heat, dulling his palate for the rest of the meal. The culprit: Chipotle’s Tomatillo-Red Chili Salsa.

Fans of Chipotle’s hottest salsa have been feeling the heat recently. Numerous reports of the fast-casual chain’s salsa being even spicier than normal have blazed in from customers. Chipotle ...