Audi Allroad 2002 AKE 220k miles - minor oil leak / seapage

[ceilidhalfie]

Hi folks, looking for some advice. For the last couple of years I have had a small oil leak from the AKE diesel. Although oil leakage is minimal, at each annual service I have to clean up the bottom of the engine and noise protector. I had to do this when I changed the cam belts etc last week (its also due a service about now). I now notice a couple of oil drops on the garage floor this morning - first time this has happened. I think it maybe because the bottom of the engine and noise protector are now devoid of a lot of oil/grit that was probably retaining any leaked oil - or the leak could be getting worse!
So wondering if you experienced chaps (Crasher?) can give me some pointers on where the leak maybe coming from.
The sump gasket is sound, as are the sump plug and crankshaft locking plug and also the sensor on the bottom of the sump.
The rhs (drivers) side looks sound - had the charged air pipe, air filter etc off when inserting the locking plate on that side. The cylinder head gasket looks fine at that side.
The left side (passenger) cylinder head cover looks to be leaking - from middle to back of seal it is "wet" with oil.
So, is it common for cylinder head cover gaskets needing replaced after 220k??
Any suggestions will be gratefully explored!