That's hard to say for sure Jamie, it depends on the grain in the wood. One thing that helps prevent it is to groove the bottom side so that any tension has room to move without causing distortion. I would be equally as concerned about seasonal movement. Wood expands and contracts across its width with humidity changes and your design has to allow that to happen.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.