If it not on the sensor, it is only visible to you while you are framing the picture and therefore not harmful to the actual picture. If it bugs you enough, you can probably just get it off with a dry clean (obviously) quetip or one of those squeezy blower things (thats the technical name by the way). Just don't rub too hard or push the dust into a place that could get on the sensor.
If you are really worried and have some extra cash, any camera store will do it for you, but there is no need to have this professionally done.