Exhaust returning from tips

["cdrugly" <tgoodwin@xxxx>]

This past Saturday I noticed light gray smoke coming from the engine. 
My butt puckered. Frantically, I lifted the louvres to find the 
source. I discovered that it was only exhaust coming from the rear of 
the chrome exhaust tips back into the engine, yet I was still getting 
exhaust to the outside as well. I took the tips off and saw no 
obstructions. Should these have some sort of heat resistant gasket or 
is this just some sort of freaky goings-on?