It depends. Generally, I will not act on anything within a couple of thousandths from my target. There is no way anyone will be able to discern the difference from target or even know that my brew was not planned that way.
I always look at the gravity reading in the context of the volumes. If the reading is pretty far off, and my volume at the end of boil is off correspondingly [i.e. high volume and low gravity or low gravity and high volume] where I know that the source of the gravity being off is due to my process. Since my process is pretty well defined in BeerSmith, such an excursion is usually a sign that I did something wrong.
The other side of that is that if the volumes either follow the gravity readings or are right on, it means that something has changed in my mash efficiency and I then start to look at my grain mill to make sure it has not changed.
In short, the fact that the gravity is off is really not much of an issue. The ramifications of it being off are worth looking at to make sure my process remains repeatable.