Asked the dealership about this as I noticed this with both our 2016 passions and was told this was perfectly normal due to the way the braking system is designed. Simple braking system, yes, there should be no further travel. I know it's disconcerting but I noticed it on my 2008 and 2009 smarts as well.
I guess though just to play it safe I would have it checked out or at least figure out if fluid level is in spec and when your fluid was last changed. Granted I'm saying this without knowing how many miles are on your smart so if it's not a lot then a brake flush is probably not needed. Also check for pad wear and any signs of leakage as that is pretty simple.
I can't say I notice it on my 2010 though the other day I did do a very hard stop and I did notice the ABS kick in and then at the end of the stop the pedal did sag for a second. But I pumped the pedal out of habit and put my hand on the parking brake to see if my brakes were actually failing and things went back to normal.