2.4 Outlander Petrol/lpg auto

Does anyone find that their exhaust gives out smoke when the engine is idling and has warmed up but the air temperature is low, say 5C or less? Smoke seems same as given out during engine warm up.

At first I wondered if it was the LPG having a higher water content in the exhaust which was condensing out at low air temperatures but I tried running on petrol and it was much the same, maybe slightly less. It doesn't seem to be there when I drive off. It doesn't use any coolant as such.

The garage has checked the emissions and they are very low and so says everything is OK.