Never had that problem... sounds like an extremely high heat.
Did you check your thermometers for accuracy?
Or did you use thermo probes?
How high was your deflector from the hear source?... Which grill?
Cooking at Mason-Dixon BBQ Services
Lang 84 Deluxe Kitchen known as "The Glamazon" , Custom Klose Backyard Chef... of Snot, and a 22.5 WSM
Lang 60 Mobile - The Damsel II, Lang 48 Patio - The Damsel, Bubba Keg Grill - RIP, Double Barrel Smoker and a BSKD