csnow is correct... again.
99% of blown head gaskets are due to overheating -- not because they somehow wear out over time. Corrosion is a factor, but the corrosion wouldn't occur in the first place if the head gasket didn't allow the water through to do the corroding.
When my head gasket was blown, I took it to at least 5 different shops and the first question they all asked me was, "did you overheat the engine?"
'01 E430, Sport 72,000 mi
'98 C280, 126,500 mi