I had exactly the same issue on my red 159 Lusso which is only 5 weeks old, so I just wanted to say that as stevel58 said it was the pivot pin at fault.
My brakes were sticking also, if I pressed hard on the brakes and released quickly the pedal had enough momentum to fully release, but if I had only applied a small amount of brake pressure, say pedal only about 1 inch depressed, then they would stay on and when it was dark I could see the brake lights still lit up in my rear view mirror, so I knew it was the pedal and not the actual brake pads.
So I would advise if you have sticking brake issues, check at night if you see the brake lights in the back, if you do then it's not your brakes but the pivot pin.
I read this post, then I put up with the problem for the last few weeks hoping that it would "wear in" and clear itself, but it didn't.
So I rang a local Alfa dealer (Donalds in Pboro), and explained the problem and that I had read on-line that it could be the pivot pin and will it be covered by warranty, they said it was unusual to have a car come in where the problem had already been diagnosed
Anyway, I took it in the next day, they confirmed the diagnosis was correct, they took the pin out, rubbed the gunk off with wire wool and then greased it and put back in, works just as it should again now, they said they hadn't actually seen this before but would be sure to remember it for any future customers with a similar issue, there was no charge for them looking at it as it is warranty work.
So thanks for the pointer stevel58, even though it now works after the last few weeks I'm still in the habit of tapping the side of the brake pedal to make sure it's off
And as a few other people have said, I also have the "mind of its own" air con unit etc, I keep an eye on the air con as it will come on as I'm driving along whether I want it to or not and the cars not misting up so it shouldn't be the visibility feature etc, so I keep turning it off for fuel economy
but I can live with it, it is a damn sexy looking car in red, I like when the posey BMW or Merc drivers cast their eyes over it!