http://en.allexperts.com/q/Social-Etiquette-Good-2570/2010/3/Retaining-political-title.htm
...It is protocol that states that if someone earns a title because they were voted into office, they retain the protocol of address after they leave...
...Senators are Senators all their lives. Governors too. Members of the House of Representatives are Mr. and Ms. while they are in office and after they leave. Presidents are Mr. President when in office and Mr. Smith when they leave. Presidents do not keep their title after leaving office. All officials who have been voted in by election will be The Honorable for the rest of their lives...
Only in the US. And as I said, it’s silly
...Senators are Senators all their lives."
Yes--and THEY SHOULDN'T BE!
That's part of the problem.
Ostrich Boy's got a damn good point.