That line struck me as very odd too.
When he took the time in one question to go back and address the "label" he was called (a Liberal), I thought I saw a mini-implosion. If he can't stand being called a liberal, he can't stand much.
Why is it that when you hear someone complain about labels, there is only one label and it is "liberal"?
I can't believe that with 10 minutes left in the debate he used an answer to attempt to illustrate he is not a flip/flopper when the expression hadn't been used in 30 minutes. That phrase must really get under his skin.