AHAH button, page reloads

What would cause the page to reload after an AHAH button submit?

The AHAH call does what it is supposed to. I see the ajax request in firebug, and I see the data return from the JS populating in my wrapper. Right after i see the wrapper populate, the page refreshes.

This is my button code, does anything stick out?

$form['myselect'] = array(
    '#type' => 'submit',
    '#value' => t('Select'),
    '#submit' => array('mymodule_select'),
    '#ahah' => array(
      'path' => 'mymodule/js/select',
      'wrapper' => 'mymodule-wrapper',
      'method' => 'replace',
      'effect' => 'fade',
    ),
  );

sometimes it will not do it the first time, but the second time i click it it will reload

i've even dumbed down my js page callback to this for testing and i get the same results:

function mymodule_js_select() {
  drupal_json(array('status' => TRUE, 'data' => theme('status_message') . 'asdf'));
}