Home button issues - software or hardware-based?

As we all know the iPhone 4 is notorious for home button problems, jailbroken or not. My question is this - has anyone determined whether it's a hardware problem or a result of jailbreaking and, I'm sure in most JBers cases, installing Activator? The reason I ask is because every time I've had to restore and re-jailbreak, I got the feeling that the home button was much more responsive during the minimal amount of time that I used my phone un-jailbroken. It's only after installing all my old JB apps/addons (including Activator) that I notice the issue returns. The multi-tasking tray lags, a single press is often registered as a double-press, a double-press usually results in a long hold, sometimes nothing happens at all, etc etc. Just wondering if it's definitely a question of bad hardware, in which case I may try to get my phone replaced by Apple, since it really is getting pretty bad. On that note, would apple replace my phone out of the initial 1 year warranty based on this home button problem? I originally bought a launch-day iP4 but had it replaced with a refurb about 3 months later for a poorly glued glass back which clicked. Thanks in advance.