And I guess I need to update this. It seems that it isn't coming from the rear. It just seeed that way while pedaling. It is only happening in the small-small combo (I know, cross chain bad, and it's a combo I won't be using). What seems to be happening is that the chain is ubbing on the inside of the big ring and catching on the pins and making a big pop each time it gets caught.

So, my question is: are there spacers that can bring the drive side crank assembly out a tiny bit? It won't take much, as the chain line is such that it doesn't rub once I shift up one cog from the smallest.