THE SPOT PRICE of oil has begun to twitch nervously upward again. That's the price of the odd lots -- a barge load here, a tankerful there. It's a highly sensitive indicator of strain in the oil markets, and a rapid rise in the spot price becomes a signal and an incitement to the exporting governments to raise the contract prices at which most oil is traded. That's what happened at the end of 1978, as the Iranian revolution gathered momentum.

It need not happen again. As long as the fighting involves only Iran and Iraq, the loss of daily production will be only slightly larger than last summer's oversupply. More important, the context today is very different from that of two years ago. In the fall of 1978, most of the oil companies had let their stocks run comparatively low and were counting on heavy imports to carry them through the winter. This year, in contrast, companies throughout the world have filled every last tank, bucket and teacup to the brim -- and are counting on nothing. Steuart Petroleum Co., Washington's largest supplier of heating oil, says that it has enough in stock right now to carry its customers through January -- and nothing so far threatens further deliveries to Steuart.

Two years ago, the major industrial economies were expanding rapidly, driving up oil consumption. Today, several are in recession and others are running in second gear. Two years ago, American imports were rising strongly and keeping world markets tight even before the strikes started in the Iranian oil fields. Today, prices are up in the United States, imports are down, and world markets have been slack for months.

But a good deal now depends on the governments of the oil-importing countries, including this one, and the state of their nerves. The trouble started two years ago among the speculators and a few companies suddenly caught short of crude oil. But it was rapidly made much worse as some of the European governments pushed companies to grab anything loose on the spot market, regardless of price. The United States abstained at first, then changed its mind and joined the grabbing.

In retrospect, the major industrial countries have agreed that the great grab of early 1979 was a dreadful mistake. They have further agreed never to do anything like that again. No one can really control speculation in uneasy times, or the occasional desperate buyer. But governments of the industrial countries have enough influence over the oil trade to prevent any long, sustained, dangerous rise in the spot prices for oil. Keep an eye on that price: it will be an interesting test of these governments' ability to work together in a common purpose that all of them, at least in principle, accept.