Dust in New 6D Body ?

Finally got FF DSLR body my film lenses fit on and something isn't right! On a plain field (sky shot) I've got a few  spots. Examination with a magnifying glass shows nothing. Tried the sensor cal but still there. Affraid to attempt cleaning as nothing is visable. Assume I can edit shots if they look bad on prints. Anyone else have a spot issue ? I heard Nikon owners are having spot problems too, bad sensors ?