I got a new gas person this year to check my boiler. He noticed that where my gas pipe comes into the house, through a hole in the bricks, the hole is sealed with cement or mortar. He said that this was bad because the expansion/contraction of the pipe against the cement would lead to wear and perhaps a gas leak. Is he correct or is he just hoping for some extra work?
EDIT: he may have said corrosion or even vibrations, I can't really remember. But how would cement cause corrosion?