Yep, sounds normal.
Since the motor is filled with syn from the get-go it make take quite a long time for the rings to completely seat. Expect subsequent miles to show less consumption, but a half quart in 3500 is well within normal.
Different oils can produce differing consumption results too. I was pretty shocked when I switched one time on our BMW 3-series. We bought it as a cpo with about 35K, was pretty sludgy inside from going WAY too long on it's oil changes. Probably only got changed twice. My favorite oil for those is the euro-spec line from Amsoil, changed it out and did a couple of short change intervals and the motor got cleaned out. In fact, did a valve cover gasket at bout 80K and it was spotless inside. It would use about 3-4 oz of oil in 6K miles, my OCI, which is about half of factory recommendation. One time I put 5w-30 signature series in it thinking that closer matched the recommendation. At about 3200 miles the oil light came on, it had used just over a quart. I was shocked because it had never done that. That motor held 7 quarts, and it had used that much. I switched back to euro-spec shortly thereafter and consumption went back to nill. Go figure, eh?
I have some concerns with the 20w recommendation. If you have 6K on the car with a fresh oil change, then see what it does for the next 3K. If the oil is filthy black at 5500-6K it should be changed anyway, the additive package could be used up. if you're down a half quart at 3K consider switching to a 0w-30. The slightly higher viscosity may well stop your consumption by helping the oil ring to seal better. I can't say for sure that would fix it, but might go a long way to improving it.