I have had some smole come out the bottom vent when the top vent is fairly wide open and the top vent is almost closed.

I have had licks of flame out the top of the dome when the fire is hot and the bottom vent open quite wide. I put the cast iron lid on and closed it down to get the top vent and lower vent to get the temp down and kill the flames.

Fire (flames) require 3 things. Heat, fuel and oxygen. Cut any one of those things off and the fire will go out - or in not start up. As long as lump is the fuel and not something like gasoline, then the oxygen is the next likely culpret.

You have fuel (lump), heat (obvious), somehow the egg got enough oxygen into the egg to cause flame.