This is correct. You can touch somewhere on the screen and the home button and the search window pops up. Usually I am hitting the very edge of the screen and pressing the home button so the search pops up. If I am paying attention and just push the home button the search does not launch...
Having this same problem where when I use the home button to close out an app it will open a new search window instead. Different from the double press opening up a google now search.