Based upon an "American Woodworker" Aug 2000 article, here is some table saw troubleshooting questions.
If the board pulls away from the fence it means what?
If it binds against the fence it means what?
What's a barrel cut and more than 1/4" deflection means what?
For the first two, I believe that it occurs when the fence and the blade are not parallel to each other and/or not perpendicular to the edge of the table.