I've noticed that a lot of the time, when people ask Obama his position on something, he'll say, "As I've said numerous times before, I support blah blah blah..."
At first I thought this was just political schtick to combat the charge of flip-flopper. But now I wonder, is this his tell? I.e., if he doesn't want to actually answer his true opinion on something, he can truthfully say, "In the past I've said that my position is..."
This way, he can minimize the number of lies he has to tell. He does it once in a prepared speech, and then in informal interviews he (perhaps subconsciously) falls back on a truthful reference to his speech.
Remember, Obama hasn't been in politics as long as someone like Bill Clinton. Blatant lying might still be hard for him.