Mitt Romney is not a governor. He is an ex-governor. The governor of Massachusetts is Deval Patrick.
In America, ex-politicians are generally called by their most recent office held as a matter of courtesy, which is why (for instance) Bill Clinton is still introduced as President Clinton and Mitt Romney is still Governor Romney.
I've always thought it's a pretty ridiculous custom. You don't see the BBC calling Tony Blair the Prime Minister, for example.
Thankfully the UK doesn't have ridiculous titles given for life.
Well played HTMLdon, good to see you around btw.
Thanks! I'm just trying to get something placed in the Naso comedy thread that isn't laughing AT me