Replaced MB Air battery, now trackpad is acting weird

Hi all, newbie here. I just replaced my original battery on my 2013 MacBook Air with an iFixit replacement, which is working great! However, now my trackpad is acting wierd: even when I just lightly tap it, it makes this thudding click sound. When I click it, it makes the usual click sound plus this new sound. The trackpad seems to still work correctly, but this is pretty annoying and makes usual light taps sounds like I'm banging on my laptop!

From what I can tell, the trackpad seems to be loose or something. I reopened the case, and unscrewed and re-placed the new battery, but this didn't help. Any thoughts or tips?