I would bet that the imports from SK in April, 2004 referenced in the Bloomberg article were 1 million barrels of gasoline (same as the 43 million gallons mentioned in teh article). That is still not very much for the US, since we consume 17 million barrels per day. I'll bet imports from SK are up to at least 2 million barrels per month by now. I'll see what I can dig up on this.
Maybe not usually, but it does happen. I recommend taking a quick look at the Explanatory Notes then look at the data.
Company Level Imports, March 2006, all petroleum products.
Shipments may not be a complete tanker, perhaps a partial filled tanker from Indonesia hauling crude stops at South Korea on the way to the US West Coast. Fills a compartment or two with gasoline for transport. But I am only guessing here, this is outside of my experience.
Although the numbers still don't match the article, I messed up the math. I was off by a factor of 10. If, according to EIA, March 2004 we received an average of 9,000 barrels per day from South Korea that (x 30 days x 42 gallons per barrel) equals 11,340,000 gallons for the month. Still not the amount from the article but a little more believable for shipping. We also received other petroleum products in the same time period. An average of 20,000 barrels per day. Shipments likely carried products such as Kerosene in separate compartments.