I concur with others that you won't notice it in photos. A bit damage in the coating would add to reflections, but you won't objectively see it.
As an illustration, how little effect stuff in the lens has on the resulting picture, there was a great blog posting Removing a Fly from ‘Weather Sealed’ Canon 70-200mm f/2.8L IS II
. Just in case should you develop dust obsession not to speak about dirt or bubbles directly in the glass.