Nissan x-Trail - Cold engine misfiring - petermcp

I have a 2012 Tekna 171 manual. When pulling away from rest with a cold engine I frequently get one or two cylinder misfires. Once the engine has warmed up it doesn't seem to happen (as far as I can tell). Has anyone else seen this? My Nissan dealer says that if there are no fault indications, it's probably ok. I'm not so sure!