I've had an Epiphone Thunderbird Pro-IV Classic for a few years now. Excellent bass with Gibson USA ceramic humbuckers in it. I believe this might've started a while ago but I paid no attention, and recently it's becoming a more noticeable issue. I've been jamming with friends and a lot of times we like to play Alice in Chains songs, and the bass lines are often a step down in tuning. When I absolutely need to play a step down, I just tune my E string down instead of the whole bass. But I've noticed when I tune it down, it doesn't go lower at first when I try it, then maybe after a second or two of turning the key, I hear a small snapping noise from the key and it's usually down to a C sharp. I also notice after it snaps the tuner feels a lot looser when I tune it back up. It's not a gigantic issue, as I'm able to tune it back up after, but I would really like to know if this could be a larger problem than I think, especially since the Thunderbird is neck through, making neck issues probably much more tricky. Any advice?