[clickman]

To close the loop on this one, the problem is fixed. One of the local indies thought it was the valve at the top of the filler tube, but discovered that that wasn't it. He then tried a number of things to diagnosis, but the only thing he could find was that the evap canister "seemed heavy". So he disconnected it and gave the car back and told me to try filling it (I needed the car back). So I did and it did in fact fill full. So the canister was replaced and it's all good.