'clicks' during ab exercises

So recently I've started going to the gym, but last night as I was doing a couple of ab exercises, I heard the 'click' you get when (I think) cartilage rubs together in my lower back. No pain or anything, but a tiny bit of discomfort mostly from being unsure if it's a big deal or not.

I do roman twists and another exercise where i bring my knees up to my waist whilst holding onto a couple of bars (so my feet don't touch the ground).

The clicks only happen on the way down, should I be worried about this?

It's fine. If you get no pain/swelling/discomfort afterwards, I wouldn't worry about it too much.

Cavitation?