Blue smoke!

Brocol

This is aimed at those with more technical expertise with engines than I have. Stuck in a long tailback on the M56 yesterday evening, stop/start crawling for about 45 minutes resulted in significant 'blue' exhaust fumes. Fortunately, all appeared well when
normal speed was resumed. Engine is Fiat 2.8 JTD (2006). Was this a result of the crawling speed or do I potentially have a problem?

On an entirely different tack, has anyone a solution for side windows which are stuck to the rubber seal so firmly, I risk damaging them if I try to prise them open?