It's normal behavior, but I dropped out of the thread because there's no way to prove it to someone used to the American/Japanese coolant systems.
Granted, a real crack can leak combustion gases into the coolant system. If that happens you'll start to see a negative effect on the running temperature.
I'd hate to see someone have a complete head job or even replace their head gasket when their car is behaving normally. If its not overheating, losing coolant, or showing any bubbles in the coolant, drive.