Toto Aquia Installation - noise

We just installed our first Toto Aquia and are concerned about a trickling noise that continues for ~15 seconds after the flush and tank refill are complete. We took the whole thing apart again and checked that everything was level.
We think its water dripping down the back of the plastic trap? Has anyone encountered this, is it normal for this toilet?

All toilets do this, but with the plastic adapter, you can hear it a little more. Nothing to worry about. As the bowl gets filled up, it's like a cup of water that is being overfilled. It takes it a moment to settle down as you stop adding water to it as it dribbles over the edge. You'll notice it, too, when you are sitting there and adding things to the bowl...the bowl is filled just to overflowing, anything that is added causes it to overflow.

Thanks for the quick reply it confirms my husband's suspicions.

We were thinking we'd mitigate the drum effect of the skirt cavity around the trap by filling the void with batt insulation to try to quiet down the dripping.