Sluggish 1.6 D2 at start up
 

I recently noticed that my 2013 V40 1.6 D2 50k miles is sluggish at initial start up, however if I raise the revs more than normal it is better. For the rest of the day when starting it is no longer sluggish. Fuel consumption is normal for me, there are no warning lights, not yet done a diagnostic test for error codes.
Volvo fitted a new fuel filter at the last service.
Any ideas?