Gustav Mahler conducted in Leipzig for two years, and if he could have heard the Leipzig Gewandhaus Orchestra's performance of his First Symphony last night at Kennedy Center it seems most unlikely that he would have been anything but delighted.

For those of us who remember the days when Mahler symphonies were unjustly neglected it seems unnatural to describe one of them as presently overplayed, but that is now true of the First. Last night's version, though, which was under that fine conductor Kurt Masur, was the freshest, most graceful one this listener has heard in quite some time.

Maybe the means helped dictate the end in this case. The Gewandhaus Orchestra simply does not have the brawny super-sound to blast away, as the blockbuster ensembles tend to do in this work--and do so tiresomely.

So Masur and his orchestra emphasized the First's lyric side. There was not the individuality of timbre or sonorous power that the Chicago Symphony or the Berlin Philharmonic would give; in fact, the Gewandhaus brass was ragged and sounded like the orchestra's weakest link.

But instead of sonic mass there was careful attention to phrasing in the harmonic and rhythmic shape of the music. Note values had been painstakingly thought out. Rhythms were wonderfully pliant; the second movement's trio, for instance, which is a gorgeous section that is like an Alpine La ndler, could hardly have been more caressingly played.

The work's many quiet moments were gentle, leisurely and vibrant. And they seemed all the more so because of the remarkable steadiness of Masur's underlying pulse. The climaxes were superbly built, and the soft passages were quieter than American orchestras seem capable of producing.

Masur is doing quite a lot of guest conducting in the United States these days. The National Symphony should grab him for some concerts.

It would be nice to say that the other work on the program, the Beethoven Violin Concerto, was just as beguilingly played, but it wasn't. The diplomatic thing to say to these East German visitors is that the performance was workmanlike.

The soloist was the orchestra's concertmaster, Karl Suske. His interpretation lacked clear-cut expressive focus. Also, he had some problems with the notes. He kept playing flat, and he fell behind the orchestra once in the opening movement. Masur did, though, conduct the register and running the orchestra equisitely in the slow movements.