Not really. If they do a repeat of the Smash Wii U's '50-fact Extravaganza' then it will easily fit the 40 min timeframe since that one was 35 min with two new character reveals. It's why I wouldn't see the 40min length as a confirmation of the recent leak like others around the internet are doing.
I think what makes it longer is that we had e3 and the recent direct which covered a lot of Smash.
Pocky Lover Boy!