Rain/roadwater splashing against crank-pulley. Slipping P/S & Alternator belts...

Had a closer look on the belts and did find a combination of issues with them.
Besides not being new (I knew that), they were pretty greasy (I've ran the engine without a PCV once, which caused some oilleaks at the front), the PowerSteering belt was a bit looser than I remembered, and the alternator belt had some misalignment with the crank pulley.
I correct the alternator-alignment with some shimming, retightened the P/S-pumpbelt, and degreased the pulleys and belt with an ample amount of brakecleaner.
I have a feeling the alternator charge at idle has improved a bit. Perhaps it was slightly slipping all the time because of it's greasiness.

Now I gots to find me some puddles to throttle through... :)