Um,
weightx (and
weighty) specify how extra space is to be allotted, so this won't make a difference in a case where the preferredSize of contained components changes.
Bryan, your code snippet lacks one very important detail: what components are used to show the numbers. To get better help sooner, post a
SSCCE (Short, Self Contained, Compilable and Executable) example that demonstrates the problem.
Unless there's more to your question than is apparent from what you've posted, why aren't you using a
GridLayout?