are you using liquid extract? sometimes that will contribute a 'twang' to batches. i would doubt that you are experiencing oxidation, but it's not impossible.
sometimes steeping/mashing grains at too high a temp will cause off flavors also.
so you just poured 200+ degree priming solution into the bottling bucket and racked on top of it? i would guess it would come down to temp pretty quick since it's not that much compared to the wort, but that may have contributed.