IPhone 4 open the recent apps with one home button click?

I got an iPhone 4 yesterday and sometimes when I try and close an app it will open the task manager is this a hardware issue or another problem with ios 7?

Added (1). I don't think the button feels sticky it feels a bit different to what my old ipad 2 used to feel like and it never does it when i press the home button on the home screen i always need to double click it i will just wait until the 7.1 update and see if it happens after that.

If you click twice it's supposed to do that if you only click once it could be that your home button is a little sticky does it feel like its a little stuck or harder to press?