I'm pretty sure Nolan doesn't think any of his movies have padding. And I'm pretty sure of all directors, he has the most authority to tell studios to piss off if they ask him to pad a movie.
Anyway, don't studios normally err on the side of a shorter movie? Most stories are about long movies being cut down to size (Black Dahlia, Heaven's Gate, The Magnificent Ambersons etc.) and made incomprehensible rather than the other way round.