IT'S ODD, when you think about it, that a nasty little controversy is swirling over whether the Israeli army misused in Lebanon one particular weapon--cluster bombs. These weapons are deadly in their fashion: designed to kill troops in the open, they spray fragments across an area the size of a football field. But they are not illegal or intrinsically more inhumane than other weapons. Many armies have them. Israel used them without political incident in 1973. Why the fuss now?

The immediate trigger is the set of restrictions that the United States imposed on Israel's use of these particular munitions, which had gotten a bad connotation from American use of them in Vietnam, after the Vietnam War ended. An incident took place on Israel's border and this gave the United States occasion to demand that Jerusalem employ cluster bombs only in authentic conventional warfare circumstances and against strictly military targets.

The Israelis deny violating these restrictions in their use of cluster bombs in Lebanon, attributing what civilian casualties there may have been to the PLO's practice of deploying military units in civilian settings. President Reagan, however, has distanced himself from the Israeli explanation by halting a new shipment of cluster-type artillery shells while continuing an administration review of whether violations actually took place.

Beyond the cluster-bomb issue, meanwhile, a broader question has been raised about whether Israel's Lebanon operations fit the general criterion-- of being essentially defensive in nature-- attached to all American arms exports. The administration is looking into that general question, too.

The whole notion of tying strings to arms exports is troublesome. If a particular weapon is so liable to misuse, why ship it in the first place? To impose the restriction conveys lack of confidence. To react to a violation can cause additional strain. Not to react conveys weakness and hypocrisy.

Thus it is that the administration now has the worst of both worlds. The Israelis contest any suggestion that they may have violated the cluster bomb terms, and so the administration has a testy argument on its hand at a moment when, in Beirut, it has far bigger fish to fry. Meanwhile, it is taxed for being namby-pamby by critics of Israeli policy.

This is not one of the great Israeli-American confrontations. It is, however, symptomatic of the unease felt by many Americans toward some of Israel's purposes and methods in Lebanon. It is unhealthy, even unseemly, to have Americans and Israelis pulling and hauling over matters like this. They need to be working together on the big issues, like peace.