Driver's Side Water Noise

The level in mine doesn't change at the moment

Might be very early days and only a very slight leak so far.
Keep an eye on it.

Trev.

FWIW Mine has had it since I bought it, recently re-surfaced as I opened up the fuel cooler so there's a bit of air in there.
If you've got the system pressure tested then you should be okay. Give it a bleed and it should sort itself out.