Hi Donald - I referred to the parade of views coming through, and was wondering whether I ought to be more concerned, or its a small matter to worry about.
I just got off the phone with the mechanic who changed the plugs and he reckons it could have been water vapour from the petrol as he had a similar client with the same complain.
He did say its nothing to worry about.
I certainly hope so.
In any event, I shall be keeping 2 eyes on the plugs in 3 months' time when the next service interval is due. Meanwhile, the 300se runs as smooth as ever.