Maybe I've missed something here. But if the OP states he bought the watch from a grey market (aka non-authorized) dealer, I'm wondering how the watch came with a genuine Omega warranty.
As for the sweep second hand, the 3330 has one of the sloppiest sweeps I've seen. My Speedy Racing w/3330 has the same issue, so I went back to the OB and examined every watch they had with a 3330. They were all the same. However, the watch has been running +1 SPD for more than a year, so I forgive the jerky sweep. Two easy workarounds - 1. Don't stare at it. The longer you look, the worse it seems to be. 2. Turn off the chronograph.