UI buttons... incorrect hover class- is it a bug?

UI buttons... incorrect hover class- is it a bug?

I have some buttons and 3 out of the 4 work totally fine.  The fourth however has a strange behavior where the hover class doesn't get properly added.. and as such doesn't always hover correctly (color change.. and the pointer cursor are wrong).

and w/ firebug open i can see the correct class "ui-state-hover" get added to the working buttons and only some of the time to the broken button.  instead i will often just see "hover" as the class, which then doesn't work w/ the UI theme. 

  1. $('.upload_img').button({
  2.         icons: {
  3.             primary: 'ui-icon-folder-open'
  4.         },
  5.         label: "Browse"
  6.         })

which produces this html :

  1. <button aria-disabled="false" role="button" name="upload" type="submit" value="logo" class="ui-button ui-widget ui-state-default ui-corner-all ui-button-text-icon     "><span class="ui-button-icon-primary ui-icon ui-icon-folder-open"></span><span class="ui-button-text">Browse</span></button>

all looks as i expect it to (and pretty much the same as the other working buttons) so i am not sure what is up.


EDITED TO ADD: i am also using this button to trigger AjaxUpload.  could that be part of the problem?  are they just not playing nice together?