Why is the Home Button loose after screen replacement?

I purchased the front panel replacement recently from ifixit, and last night I had a chance to replace my shattered screen (*tear*). Anyways I get done with the entire process and when I turn around my phone to admire my new shiny screen, I notice the home button is loose! I'm not sure if loose is the correct word but it seems as if it's deflated? If you tap it with the edge of your nail it will rock back and forth like a see-saw. The button overall still works, but this is super annoying.

My question, could it be something I missed during reassembly? And if so does anybody have an idea what it could have been? I looked at the comments on the guide and no one is mentioning this issue.

A second thought, this display seems thicker compared to my last display, but I haven't confirmed this yet. I received my phone on its release so I'm curious if something has changed in the parts since then.

I know a tear down is imminent, but I don't want to go down that road without knowing what to fix, or a suitable hack I could try to make it better.