I have exactly that problem. I park on a small incline and my fuel gage is always off by 2 small lines. When I stop and park it on level ground and restart, it is ok. I think it does change back after I have been driving about 15 min. However, the digital readout on fuel used seems pretty accurate. It probably measures fuel going into the injection system, and thus is only looking at fuel actually used (I think).
Opps, I'm now not so sure about my comment on the digital fuel used readout being more accurate. Went for a ride today, and I think it was reflecting the fuel guage. I'm gonna have to start writing down the numbers at start and finish.