I guess you will find out for sure at the same time as your central locking, when you take it for test & it has an emissions test.
A little white smoke is often present on start up particularly when the air tenps are down towards zero.
What you are seeing is most likely condensation – steam in fact- cold engine & cold exhaust system meets hot exhaust gas on start up & the moisture starts to boil off, just like a kettle.
