Vinyl Planks "click" when tapping on joint directly

I am in the process of putting Golden Arowana vinyl plank flooring in my basement. I went around the room and the floor seemed to be level (or within tolerance of 3/16"). I am using an underlayment (Pergo Gold) along with a pad-attached plank. The manufacturer of the plank states that adding an additional underlayment was optional but it doesn’t void the warranty of the planks if one is added.

Before I started with putting down my first row I put together 4 boards (2 rows, joints staggered about 8") so that I could move it around the room and see if there were high or low spots I might have missed. If walk along the planks normally everything seems fine: I don’t hear any popping, there aren’t any peaks, etc. However if I take my finger or toe and tap directly on the joint I can hear the tongue and groove making contact with each other, thus making a ‘click’ sound when I tap on it. I pulled up a section of the underlayment and set the planks directly on the concrete and the sound was still present.

This is my first time putting down a vinyl plank floor so I am not sure if this sound is "normal" and the planks will firm up over time or if this is indicative of a problem with the concrete floor being to far out of level, if I have seated the joint incorrectly somehow, etc.

I have tried googling about this but most of the results that came up were about the sounds the floor makes when you walk on it. Is this sound normal or have is something wrong?

Any help or advice would be greatly appreciated!

EDIT
This appears to be me just over thinking things. I got about 6 rows laid down and everything sounds great. Thanks for the feedback everyone!