make sure the adapter is tightened down evenly. look at the gaps between the two pieces and make sure they're the same amount.
there can be play in the sprocket holes, however slight, and it'll make a big difference on the chain.
as an example, almost every bicycle has a tight spot and a loose spot in the pedal chain. as you only pedal hard going forward, the hole (or holes) on the sprocket will deform from the torque. in serious cases on one piece cranks, the sprocket will click back and forth because the hole enlarged.
first, check the gaps like i typed above. make sure the sprocket doesn't wobble side to side at all. the adapter could be very slightly crooked, or the sprocket could be warped or tightened unevenly. it's only aluminum, and aluminum will flex and bend and distort. so will steel, for that matter.
with the chain off, spin the wheel and hold a marker near the top of the sprocket, getting it closer and closer till it finds the high spot. mark the sprocket and the adapter in that spot. loosen up the three bolts a little and tap it down on the high spot and re-tighten. if there's still a high spot there, take the sprocket off and move it over one hole. if the high spot is on the same mark on the sprocket, the sprocket's a little off. if the high spot is on the spot of the adapter, the adapter's a little off.
it could be that the sprocket hasn't worn into the chain yet, also. after another half a tank, it might go away.
or maybe Jim just didn't get enough sleep the night before making yours...