Alternator or serpentine noise

[ipse]

New (2000km) MZ3 GX Sport. I started to notice that on the passenger side the only engine noise that can be heard (or very predominant) is the one coming from the alternator belt (or what I assume it's the serpentine belt below it).
Is it normal for a new car (I wish I had a video to substantiate the claim)?
Obviously less noticeable when the engine is at 80C than at 50C.

Older posts in this forum talk about the belt tensioner, but c'mon, this is a new car!
Not that anything would surprise me :)

Suggestions on what/how to check (other then the obvious "go to see your dealer") are most welcome...

[Shinglez]

Is it like a hissing noise? The same thing happens to me, but only when it rained all night or if the engine is really cold. It's pretty normal from what I understand.

[ipse]

Well...like I said, need to pull my phone and take a video. It is little bit more than hissing and definitely louder than I expected. To the point that I thought initially something rubs against the belt or pulley.