Thermal shock does not mean cold water - just cold relative to the heat of the glass (ceramic). You were lucky.
But I have also overshot on my Primo and it is a B. I think I just used too many starters in the lump. My PartyQ controls a fan but even with the fan not running because the temp is too high there is still a wide open intake of air through the fan unit. I had to take off the PartyQ and squeeze closed the vent manually to tamp down the fire.