If it was graded BGN or higher then the shutter should be working properly, or at least close enough.
If it was rated anything less, the KEH descriptions say that there may be things wrong, caveat emptor. In either event, the time I had a problem with something from KEH they were very nice and did a quick exchange.
Having said that, if you really love the camera otherwise (higher speeds ok? like the camera?) you can have it serviced, but it costs somewhere around $200.