Noise coming from RO/DI

[Wrench]

I just got my new RO/DI unit hooked up at the apartment. It's a compact reefkeeper model from AirWaterIce. It's working fine making a good amount of 0 TDS water already but it's making a hissing noise that sounds like it's coming from the flow restrictor valve. Anyone know what that could be about? They're closed now but I sent them an email so hopefully I will hear back tomorrow morning but I wanted to ask here in the meantime.

[JetCat USA]

that's normal while it's making water.

[AZDesertRat]

Yep perfectly normal.

[Wrench]

cool thanks. I was concerned because the manual specifically states that the unit should make no noise at all.