FormItem class doesn't have any styles or properties to control corresponding label alignment. Right alignment is applied by default and it's good idea to keep it "as is", because some usability researches say it's more friendly for user. Though if you want to make your FormItem label left aligned, use ExtendedFormItem class instead of regular FormItem:
ExtendedFormItem label is left aligned by default, but you can set labelAlign style to "right" if necessary.
