And congressmen don’t become president.
I think you mean House members don't become president.
I'd normally give you a point for that (seeing how I've made the same observation in the past), but when's the last time a former Speaker of the House ran for president?
That's a position that's much closer to the top of the food chain than mere member of the House, and in Newt's case, he was such a strong Speaker, that he elevated the power of the House to that of the Executive branch.
Say what you will about that man, but that's his legacy. I'd say that it's weighty enough to break the mold on that one tradition.