Though it sounds contradictory, my experience has shown, on multiple vehicles, if you use "Good" oil, it tends to use more of it.
I too use Top Fully Synthetic oils and it does seem to be consumed more quickly than regular "Dino Oils".
The downside to the increased protection from friction and heat is that it also makes it's way past seals, rings, and gaskets and "creeps" around when warm, leaving a oily film, rather than drips and puddles (especially in older rigs with looser clearances on all items listed) .
So, you'll see a small increase in MPG, and much longer service intervals. This probably makes the small consumption even more obvious.
If you were changing oil every 3k miles, you probably not even notice much loss on the dipstick. But, as these good fluids allow you to push your maintenance intervals out to 7k to 10k miles or more, you will notice more of it missing.
One should always keep an eye on the oil level regardless. But, we get lazy and forget the "old" days, where fluid consumption, massive leaks and blue smoke were just the norm. Especially on the old big blocks in hard working trucks of the past. Everyone used to just carry quarts of oil, trans fluid, rags and funnels around all the time, as they needed a 'top off' with every fuel stop.
Long story short, it is perfectly acceptable.
