Blue smoke on idle - blocked breather or VSOS?

[Error404]

Getting some blue smoke on idle when warm (7A)

I've not noticed it before now, it seems to have come on quite quickly.
Doesn't smoke as far as i can tell in normal driving an doesn't seem to be losing any oil
I thought worst case scenario was valve stem seals , but wondered if a blocked crank case breather could also be the culprit? i know the PCV system can throw up smoke on the S2, but wasn't sure if the 7A would exhibit the same symptoms if the crank case breather was full of crud?

I'm going to clean it out as a matter of course over the weekend, but be useful to get peoples thoughs.... also be handy to know how quickly the VSOS could go south if it is indeed those little blighters that are causing trouble?

[quattroTurbo]

If it was valve stems or seals then it would smoke on start up. It might pay to do a leak down and compression test to be sure.

[Error404]

yeah i'll get that done as well as cleaning out the breather for good measure