That was until the Arab musician claimed otherwise:

The 28-year-old resident of the Farah refugee camp in the northern West Bank studies music at Al Najath University. "I did not offer them to play," he told Haaretz on Tuesday. "They asked me to open the case and show them the instrument, which was fine by me. But then they asked me to play; I did not offer to play. That does not sound logical. They asked me to play something sad, to match their mood.

"I felt humiliated," Tayam said Tuesday. "I always identified with the Jews who suffered in Europe [at the time of the Nazis] and after that they come and do the same thing to us."

When asked if perhaps the soldiers wanted him to play to ensure that the violin was not booby-trapped or contained explosives, Tayam said, "it doesn't make sense that they thought there were explosives in the violin. If they thought that, they would have made me move some distance from them [before playing], fearing I might blow up. I do not understand why they forced me to play. Most of the soldiers at the checkpoint know me, as I work there twice a week. The problems arise when new soldiers come."

Seemingly quite logical. But wait. Though it's not exactly the same thing, my brother says that when gets on a bus at the Central Bus Station in Tel Aviv he is often asked to open his Tefillin (phylacteries) bag. And I remember being asked at the airport to turn on my cell phone. If the cell phone had been boobytrapped, it would have killed the guard too. Most likely asking someone to take an action is to prove that an item is harmless. If I had refused to turn on my cell phone, it would have indicated that I had something to hide.
Now Frimet Roth adds some useful information. Apparently it's not uncommon for musicians to be asked to play:

Also responding in a letter to Haaretz was a former principal violinist for the Israel Philharmonic Orchestra. He writes: "Over a decade ago, I found myself in a very similar situation. During a concert tour in Great Britain, we arrived at Belfast airport and at border control I was asked to open my violin case and immediately afterwards even to play for them? It is appropriate to point out that musical instrument cases have been used at times to hide weapons." (He cites a movie and television show as examples.) In letters to the Jerusalem Post, other musicians described similar requests to play their instruments at overseas airport inspections.

Nevertheless, the notion that the request of this Palestinian to play was humiliating and unjustified could not be laid to rest. Even the IDF bought it in revising its statement to deny that the request had been made at all. The Palestinian had volunteered to play, was its claim now.

If you think about it, it makes sense. Maybe the violin wasn't boobytrapped. But maybe its hollow was still being used to smuggle some sort of contraband. Likely the person carrying it would not be trained in its use. An inability to play music successfully would likely be a signal that the person transporting the musical instrument has something to hide. It need not to have been boobytrapped in order to pose a danger to Israel.
And of course as Mrs. Roth notes, cases for musical instruments are not always innoucuous.

The story of the soldier and the violinist has been blown way out of proportion to its significance. I too would like it removed from the media burner. But not before another musical instrument gets its deserved mention.

I'm referring to a guitar. One that also grabbed a few headlines on 9th August, 2001.

On that morning, Izzadin Al-Masri, the newly-religious son of a well-to-do Palestinian restaurateur, passed through a machsom -- a checkpoint -- on the edge of West Jerusalem. Accompanied by a Palestinian women dressed as an Israeli to allay suspicions, he strode into the center of the city. A guitar case was slung over his shoulder. At 1:45 pm, he reached the intersection of King George and Jaffa streets. The restaurant was packed with mothers and children. This was lunch time, and the country's schools were closed for summer vacation. Al-Masri entered easily -- there was no security guard. Seconds later, he activated the explosives in his guitar and murdered fifteen Israelis in cold blood. My daughter Malki, 15, was one of them.

It's worth noting that a search for "violin" on the Washington Post website doesn't turn up any follow up acknowledging that the Arab claim may have been false.
Crossposted on Israpundit and Soccer Dad.