Hi everyone, i've got this small but very annoying problem and i hope someone know what's causing it!

So, it's a 2005 S60 2.5T AWD with nivomatic suspension and after it's been parked for a while (like 1-2 days) the suspension get's a bit soft and sinks down a bit but as far as i know that's not really a problem since it a normal behaviour (correct me if this is wrong) .
BUT the thing is that it's making the most annoying sound in the world at first! This sound keeps on for about 5-10 minutes of driving until the suspension has gotten to it's real height/"strength" and it's driving me crazy..

Here is a couple of recordings (i put my phone in the backseat during this) that shows the sound, please listen to it and see if you got any clue of what's the cause of this. I'm lost

http://privat.bahnhof.se/wb691989/lj...9%20073009.mp3
http://privat.bahnhof.se/wb691989/lj...9%20073009.m4a (in case the mp3 is not working).

You can here the sound clearly at 20 seconds, 46 seconds and around 1 minute 16 seconds.

One guess is that the right rear nivomatic is in need of a replacement and the sound is coming from the actual shock?